Militants attacked a crowded mosque during Friday prayers in the Sinai Peninsula, settling off explosives, spraying worshippers with gunfire and killing at least 184 people in the deadliest ever attack on Egyptian civilians by Islamic extremists, AP reported.

The attack targeted a mosque frequented by Sufis, members of Islam’s mystical movement, in the north Sinai town of Bir al-Abd.

The militants opened fire from four off-road vehicles on worshippers inside the mosque during the sermon, blocking off escape routes from the area by blowing up cars and leaving the burning wrecks blocking the roads, three police officers on the scene said.

No claim of responsibility has yet been made.