A train crashed into a school bus at an unmanned railroad crossing in northern India on Thursday, killing 12 children, police said.

Top police officer O.P. Singh said the bus driver also was killed.

Another 12 children were injured in the crash and taken to a hospital in Kushinagar, a town 200 kilometers (125 miles) southeast of Lucknow, the capital of Uttar Pradesh state.

The children were on their way to school when the train hit the bus.

"Most of the victims died on the spot," area police officer, Ramkrishna Tiwari, said by phone.

The dead children were all under the age of 10, he added. The death toll could rise as the condition of some of the children was said to be critical.

Police blamed the driver for the accident. "The accident occurred due to his negligent driving. He was listening to music on his headphones and did not stop the bus to check for the approaching train," Tiwari said.

State authorities have ordered an investigation while Indian leaders offered their condolences to the families of the victims.

Shocked parents and relatives of the children rushed to the accident site and the hospital after hearing the news of the crash.

Accidents are common on India's railroad network, one of the world's largest with 23 million people riding daily on about 11,000 passenger trains.

Hundreds of crossings are unmanned, especially in rural areas. Poor finances limit efforts by rail authorities to staff the dangerous crossings around the clock.

Vehicle drivers often try to cross the unmanned rail track in a hurry, causing accidents.

This is the second major accident involving school children in a little over two weeks.

At least 24 children and three adults were killed when a school bus plunged off a mountain road in the northern Indian state of Himachal Pradesh on April 9.