TRIPOLI, Lebanon (AP) — A bomb ripped through a bus carrying civilians and members of the military during this morning’s rush hour in the northern Lebanese city of Tripoli, killing 18 people and wounding 40, security officials said.

The officials said the dead included 10 off-duty soldiers.

The bomb was planted on the side of a main street and went off as the bus passed by. The streets were filled with people heading to work, which contributed to the many casualties, the officials said.

The military had no immediate comment. The security officials spoke on condition of anonymity because they were not authorized to speak to the media.

The blast raised suspicions that al-Qaida-inspired Islamic militants may have sought revenge on the military for its assault last year on the nearby Palestinian refugee camp of Nahr el-Bared, a one-time bastion of the Fatah Islam group. The monthslong battle killed hundreds and eventually drove out Fatah Islam.