A bus full of high students was returning late Wednesday from a trip to Bali when a semi-trailer veered into its lane and crashed head-on into it, police said. A second truck then smashed into the back of the bus on the busy highway near Situbondo, some 800 kilometers (500 miles) east of Jakarta.

Situbondo Police Sgt. Iswahyudi, who uses one name, said the truck driver had fled the scene and was wanted for questioning. He said the truck's brakes appeared to give out as it descended down a hill toward the bus, he said.

"It is the worst the traffic accident so far on this route," he said. "We are still questioning witnesses to find out what happened and we want to find the truck driver to question him."

At the town's hospital, authorities had begun the grisly task of identifying bodies. Many of the victims, authorities said, had been trapped in the bus and were burned beyond recognition. So far, 26 victims had been identified.

"We saw the bodies," a hospital nurse who identified herself as Kusniani. "They were badly burned. It was horrible."

Traffic accidents are a frequent hazard of Indonesia's often-crowded and poorly maintained highways. Motorists often flaunt traffic laws and police can be bribed to ignore infractions such as speeding.

In April, two buses collided on a toll road outside the capital Jakarta, killing 11 and injuring 25.