(AP) A suicide bomber detonated an explosive belt in a bus as it was about to depart Baghdad Thursday for a Shiite city in the south, killing up to 30 people and wounding nearly 40, police and hospital officials said.

Most of the dead were in the bus, which was gutted by flames, and the rest were gathered around a food stall nearby, police said. The Kindi hospital said at least 37 were injured.

The blast occurred a week before national elections, and officials had warned of a surge in violence ahead of the balloting. Several other explosions rumbled through the heart of the capital Thursday morning.

Witnesses told police that the attacker left a car, boarded the bus and blew himself up as it was about to leave for Nasiriyah, 200 miles southeast of Baghdad, police Lt. Ali Mitaab said.

Fire swept through the bus following the blast, trapping passengers. Their charred corpses remained in their seats, their faces starring out through the shattered windows. Police climbed over the top of the vehicle inspecting what remained of luggage.

The attack occurred at the major bus station for vehicles headed to the mostly Shiite areas of the south.

In August the station was the scene of a horrific triple car bombing which killed at least 43 people and wounded 89.