A priest and a witness say masked gunmen in central Libya have kidnapped 20 Coptic Christians from Egypt.

Abu Anas al-Libi, a man accused by federal prosecutors of being an al-Qaida member involved in the 1998 bombings of U.S. embassies in Kenya and Tanzania, died of complications from liver surgery, his wife said Saturday.

Al-Qaeda’s branch in Yemen threatened an American hostage who was the target of a rescue attempt by U.S. special forces last month, warning Washington in a video released Thursday not to try again, and giving it three days to meet unspecified demands.

Egyptians are bracing for potential violence ahead of a planned major protest Friday by Islamists calling for the toppling of the government and the defense of their religion, with security forces vowing to confront any unrest with “lethal force.”