The Obama administration said today it supports an Israeli investigation into the violence on board a ship carrying aid to Gaza that left nine people dead, but urged it be "prompt, impartial, credible, and transparent."
Secretary of State Hillary Clinton said the probe could include international participation to ensure its credibility.
White House spokesman Robert Gibbs echoed Clinton, telling a news conference, "We are open to ways to assure a credible investigation, including international participation."
The measured but firm language came a day after a bloody confrontation in which Israeli commandos rappelled onto six ships carrying activists and supplies tried to break Israel's isolation of the embattled Gaza enclave.
The incident triggered fierce international outrage. Egypt, which enforces the blockade along its border, essentially broke with Israel today and temporarily opened its main crossing into Gaza.
And the organizers of the Freedom Flotilla announced today that two more ships would be sent to challenge Israel's stranglehold around Gaza.
Israel said 37 activists who were aboard the ships were hospitalized, including four who were in serious condition. Many of the activists, including at least four of the dead, were from Turkey.
Clinton today held a pre-scheduled meeting with the Turkish foreign minister that lasted over twice as long as expected. The minister ignored questions from reporters after the meeting, but said earlier in the day Turkey wanted the U.S. to issue a stronger condemnation of the attack.
At a press conference later in the day Clinton made no such condemnation, but urged both sides to be careful not to further enflame tensions.
"We support in the strongest terms the Security Council's call for a prompt, impartial, credible, and transparent investigation... We are open to different ways of assuring a credible investigation, including international participation," she said.
Clinton in her statements added, "The situation in Gaza is unsustainable and unacceptable. Israel's legitimate security needs must be met just as the Palestinians' legitimate needs for sustained humanitarian assistance and regular access for reconstruction materials must also be assured."
Americans Were Injured in Israel's Attack on Aid Flotilla
The U.S. also confirmed today that Americans were aboard the aid flotilla and that several were injured.
Embassy spokesman Ruben Harutunian told ABC News that "at least a few Americans [were] slightly injured."
"We originally had a list of around 15 people, but then some were added and some taken off. Some are in immigration, some in detention, some in hospitals. Consular officers have been trying to get access. We're still working on the ground to identify them and get an accurate number," Harutunian said.
Among the Americans on board the flotilla was former U.S. ambassador to Mauritania, Edward Peck. His wife told the Associated Press that she had received an e-mail from Israel's foreign ministry informing her that her husband was fine and on his way home.
Israel said today that 37 of the flotilla's activists were hospitalized in Israel with injuries, including four who were in serious condition.
Israel and Egypt ordered a blockade of Gaza three years ago after the militant group Hamas forcibly took control of the strip of land wedged between Israel and Egypt.
Egyptian President Hosni Mubarak ordered the opening of the Rafah border crossing with Gaza today. Egypt's governor of northern Sinai, Murad Muwafi, told the Associated Press that the crossing should be open for several days "to alleviate the suffering of our Palestinian brothers after the Israeli attack" on the flotilla.
The United Nations Security Council issued a statement calling today for an "impartial, credible and transparent" investigation conforming to international standards for yesterday's Israeli commando raid of the Gaza-bound flotilla.
The Council also requested Israel release the six ships in the convoy and the civilians in custody, and allow full consular access for the involved countries to reach their dead and wounded.
About 480 pro-Palestinian activists from the Gaza-bound flotilla captured in the raid have been detained at a prison in the Israeli port city, Ashdod.
Harutunian said that at least four of the reported nine dead are Turkish. He had no details on the injured.
New details of the nighttime raid today emerged as people released by Israel arrived back home and described what happened.
"They came up and used plastic bullets, we had beatings, we had electric shocks, any method we can think of, they used," Greek activist Dimitris Gielalis, who had been aboard one of the six ships the Sfendoni, told the Associated Press.
Gielalis, who returned home today, said the boat's captain was beaten for refusing to leave the wheel and a cameraman filming the raid was hit with a rifle butt in the eye by Israeli soldiers.
German lawmaker Hoeger said the women aboard the passenger ship Marmara said the women were checked one by one. "Our personal belongings were taken away. Then we were handcuffed with cable retainers and brought to the upper deck."
"They were obviously looking for weapons. They raided and slashed all the suitcases of all passengers and everything was all over the place," Hoeger said.
Aris Papadokostopoulos, who was aboard the ship Free Mediterranean that carried mainly Greek and Swedish activists, said his ship was carrying a cargo of wheelchairs, building materials and medicine.
No one resisted on the Free Mediterranean, he said, but people on board were struck by the Israelis. "Some people were hit by clubs and electric shocks," he said.
The Israelis insist that they fought back after their soldiers were attacked by the ships' passengers with metal rods and pepper spray and point to video of the raid showing the soldiers being struck and one soldier being tossed over the side of a ship.
Turkish Prime Minister Recep Tayyip Erdogan today called the raid on the ships a "bloody massacre… that deserves every kind of curse." Turkey, which had long been one of Israel's few allies in the Muslim world, withdrew its ambassador to Israel on Monday, stating the already strained ties could be damaged, possibly irreparably.
A New Flotilla Being Prepared to Run Israel's Gaza Blockade
Dr. Anat Lapidot-Firilla, an expert on Turkish policy from the Hebrew University of Jerusalem faculty, called the ambassador's removal a very serious move.
"In diplomatic terms, the next step is to send the Israeli ambassador back home, which would mean the end of the relationship today," she told ABCNews.
Lapidot-Firilla said Turkey is probably expecting an apology from Israel. "Regardless of the nature of their activism, they are Turkish and it needs some answers from their point of view," she said.
The Arab League has called an emergency meeting to be held today in Cairo. Palestinian President Mahmoud Abbas has declared a three-day period of mourning.
As the condemnations escalate, another ship is on its way. The MV Rachel Corrie, its namesake the young peace activist killed by a bulldozer in Gaza, is a converted merchant ship set to reach Gazan waters en route from Ireland.
"This is not the end of our struggle to break the siege," co-founder of the Free Gaza movement and flotilla organizer Greta Berlin told ABC News. "The mission is underway. Our goal is still to reach Gaza to unload the tons and tons of cargo that's on its way."
The MV Rachel Corrie has very few people aboard, Berlin said, as it is a cargo ship and not a passenger boat. The flotilla was Free Gaza's ninth voyage by sea.
The international reaction to the raid has been "horrific, as far as Israel is concerned," said Dr. Robbie Sabel, of Hebrew University of Jerusalem's law faculty. "Civilians were killed and nobody likes to see civilians killed," he told ABC News.
The European Union, the U.N., and a growing number of international observers say that Israel's policy of isolating the region is unsustainable, calling for Israel's blockade on Gaza to be immediately lifted.
Sabel said that under international law, Israel's actions are legal in terms of the blockade. "Israel is in a state of armed conflict with a Hamas regime in Gaza, which Hamas does not deny," he said. "Under the laws of armed conflict, a naval blockade is permissible subject to restrictions — which Israel complied with."
Israel's Defense Minister Criticized Over Flotilla Raid
Israel warned the ships to re-route, keeping with the blockade law that maritime traffic must be warned.
"If it was a combatant vessel, it could be attacked. They couldn't be attacked because they are civilians, but they could be arrested," Sabel said. "With the exception of one vessel, the captains complied and sailed into the Israeli port peacefully."
Fallout from the mission is seen throughout today's Israeli newspapers, filled with criticism over the mission.
Shalom Yerushalmi in the Israeli daily newspaper Ma'ariv described the fallout within Defense Minister Ehud Barak's own party, saying that a contingent of Labor Party members, including former defense minister Amir Peretz, may demand a resignation from Barak, who they say "acted irresponsibly and with injudicious force."
Columnist Sever Plotsker of Yediot Aharonot is calling for Barak's resignation now. "There isn't a broom broad enough to sweep this failure under the rug," Plotsker wrote.
About 10,000 Turks marched in protest in Istanbul and Ankara. Public protests also ensued in Amman, Athens, Beruit, Cairo, Geneva, Ireland, Karachi, Lahore, throughout Lebanon, London, New York, Paris, Sarajevo, Tehran, Thessoloniki, Tripoli and Washington, D.C.
ABC News' Clark Bentson and the Associated Press contributed to this report