ALGERIA — An American worker at a natural gas complex in Algeria has been found dead as U.S. officials continue to work to free other Americans still being held by Al Qaeda-linked terrorists on the third day of a hostage standoff.

The Associated Press is reporting that Texas resident Frederick Buttaccio died of a heart attack as the Algerian military attempted to re-take the complex in northern Africa.

Algeria's state news agency says 650 hostages have been freed from a gas plant; 573 of them are Algerian.

U.S. officials have refused to confirm the number of Americans still captive or unaccounted for because they say that might compromise their safety.