A bus laden with shrapnel-packed bombs raced into the capital's crowded business district Thursday and exploded, killing at least 32 people and wounding more than 300, authorities said. Suspicion fell on guerrillas of the nation's Tamil minority.

The bus, empty of all but the driver, blew apart outside a train station, ripping the fronts off buildings and shredding dozens of vehicles. The dead included at least three children from schools in the area and two police officers, police and defense ministry spokesmen said.Books, a plastic lunch box and children's shoes were strewn near an overturned van at the scene. Hundreds of injured were rushed to Colombo's main hospital, and weeping parents rushed to the area to try to account for their children.

There was no immediate claim of responsibility, but police Superintendent Palitha Perera said "it definitely looks like the work of the Tigers." The Liberation Tigers of Tamil Eelam are the main separatist force on this island nation.

Defense Ministry spokesman Sarath Munasinghe said the driver of the bus had run a stop sign at a police checkpoint, prompting police to give chase. The bus "mowed down" a policewoman who had tried to stop it, Munasinghe said.

Munasinghe said the bus's route would have taken it down the same road used by government ministers on their way to parliament, which was in session.

The driver of the bus, believed to be a suicide bomber, was among the dead.

The front of the train station was badly damaged, and the police station slightly damaged. At least 40 vehicles on the streets were destroyed and about 50 nearby shops were damaged, police said.