"The site was attacked and occupied by a group of unidentified armed people at about 0500 U.K. time," said BP. "Contact with the site is extremely diffficult, but we understand that armed individuals are still occupying the In Amenas operations site."
Defense Secretary Leon Panetta said he didn't know whether there was any connection between the hostage-taking and the French military operation in Mali. "I do know that terrorists are terrorists," he said. "And terrorists take these kinds of actions not just in Algeria, they take them elsewhere."
"By all indications, this is a terrorist act and the United States strongly condemns these kinds of terrorist acts," said Panetta. "It is a very serious matter when Americans are taken hostage, along with others. ... I want to assure the American people that the United States will take all necessary and proper steps that are required to deal with this situation."
Bazi Kanani and Dana Hughes of ABC News contributed to this article.