Twenty-two people, including three children, were killed and three others injured when an Ahmedabad-bound luxury bus collided with a truck at Narmada Chowkdi in Bharuch district of Gujarat early on Wednesday, police said.

The bus caught fire immediately after the collision, burning the passengers beyond recognition, G S Malik, Deputy Superintendent of Police, Bharuch said, adding the bodies have been sent to Civil Hospital for post-mortem.

"Only after the post-mortems, we will be able to ascertain how many of them were male and how many female," he said, adding that DNA tests will also be done on the deceased to find out the relationship between kins.

"The bus had only one entry and exit point. As soon as it hit the truck, the panicky passengers ran to the back of the vehicle and were trapped when fire erupted from the rear portion," he added.

The fire intensified due to foam seats and other inflammable materials in the bus, sources said. Meanwhile, the injured were admitted to a hospital in Bharuch but discharged after first aid, he said.

Many passengers are believed to be from Mumbai, police said, adding the exact details will be known only after getting information from the agency running the luxury bus.