Two Israeli tourists and their Egyptian guide were killed Sunday when a gunman opened fire on them and a group of travelers in Egypt, according to the Israeli Foreign Ministry.

The attack unfolded in Alexandria and was allegedly committed by a local resident, the Foreign Ministry said. The tour guide was an Egyptian, according to the Foreign Ministry.

The shooting left at least one other Israeli tourist injured, the Foreign Ministry said.

Israeli officials -- including the Israeli Embassy in Cairo, the Prime Minister's Office and the Israel Defense Forces -- are working with Egyptian authorities to return the slain Israeli citizens to Israel as soon as possible, the Foreign Ministry said.

-ABC News' Becky Perlow

More than 500 people have been killed in Israel and another 2,000 injured as rocket attacks and fighting continued between Israeli forces and Hamas militants, the Israeli Health Ministry said Sunday.

At least 30 Israeli police officers have been killed in the fighting, mainly in Sderot, where Hamas gunmen took control of the police station.

Meanwhile, fighting is still ongoing in six places, including Sderot -- which sits just two miles from the border with Gaza -- even after the police headquarters standoff ended and a rocket injured four people on Sunday morning.

On Saturday, graphic video showed dozens of dead bodies, bullet ridden homes and vehicles following an assault by armed militants.

Israel has also opened a hotline for family members who can come forward to give DNA samples to help identify those who have died.

Early Sunday morning, Israel police said in a statement, "The first phase ends in these hours by the destruction of the majority of the enemy forces that penetrated our territory. At the same time we started the offensive formation and it will continue without reservation and without respite until the objectives are achieved."

Israeli police announced the cabinet decided the supply of electricity, fuel and goods to the Gaza Strip will be suspended.

"We will restore security to the citizens of Israel and we will win," Israeli police said.

At least 500 people have been killed in an explosion at Al Ahli Arab Hospital in the middle of Gaza, according to the Gaza Health Ministry.

The hospital served as a shelter for thousands of residents who fled their homes in northern Gaza.

The Israel Defense Forces denied responsibility for the explosion, saying a failed launch by the Palestinian Islamic Jihad caused the blast.

"From the analysis of the operational systems of the IDF, an enemy rocket barrage was carried out towards Israel, which passed in the vicinity of the hospital, when it was hit," IDF said.

The World Health Organization condemned the blast and called for "the immediate active protection of civilians and health care" workers.

This hospital "was one of 20 in the north of the Gaza Strip facing evacuation orders from the Israeli military," the WHO said in a statement. "The order for evacuation has been impossible to carry out given the current insecurity, critical condition of many patients, and lack of ambulances, staff, health system bed capacity, and alternative shelter for those displaced."

Palestinian Authority President Mahmoud Abbas has declared three days of mourning following the attack.

-ABC News' Will Gretsky