A police official says nine schoolchildren have been killed and 20 others injured when a school bus collided with a truck in northern India.

Police officer Vishnu Khatri says the crash happened early Tuesday as the bus carrying around 30 children collided head-on with a truck in Hanumangarh in Rajasthan state.

At least seven children died instantly, while two others died in a nearby hospital, Khatri said.

Police have launched a search for the drivers of both vehicles who fled after the accident.

Local residents said the bus driver was trying to overtake another vehicle when the bus crashed into the truck coming from the opposite side.

Hanumangarh is about 350 kilometers (220 miles) northwest of New Delhi.