The bus was transporting students to a school in Etah district when the deadly accident happened.
A truck collided with a school bus in India's Etah district in Uttar Pradesh state on Thursday killing at least 13 children and injuring over 40.
The school bus was reportedly carrying around 50 children when it was hit by a speeding truck. Local media cited fog as the main cause of the accident.
A large crowd gathered around the spot as workers tried to rescue trapped children. Senior police personnel and district administration officials also rushed to the scene.
Police said the death toll was likely to rise.
"Some children are critically injured and they are being treated. Senior officials are at the spot and the rescue operations are ongoing," said Lucknow Additional Director General of Police Daljeet Chaudhary.
India has the world's deadliest roads, the result of a flood of untrained drivers, inadequate law enforcement, badly maintained highways and cars that fail modern crash tests.