At least 20 people were killed and 15 seriously injured after the state-run bus they were travelling in was hit by a truck in Tamil Nadu’s Tirupur district early on Thursday, officials said.

The bus belonged to Kerala State Road Transport Corporation (KSRTC) and was going from Karnataka’s Bengaluru to Kerala’s Ernakulam when it was rammed by the truck in Avinashi town in neighbouring Tamil Nadu at around 3am.

Initial reports suggest the truck carrying tiles and marble jumped the divider and hit the bus. The truck driver is among those killed in the accident. Forty-eight passengers and crew were travelling on the bus.

The operation to rescue the trapped passengers was delayed because the accident happened in a secluded spot. Rescuers had to break open the badly mangled bus to rescue the injured passengers.

Ajay Santhosh, one of the travellers, said he was in deep sleep when the accident took place. He said people sitting on the front row suffered the maximum impact.

Santhosh alleged help came late.

The Kerala government rushed the managing director of KSRTC to the spot.

Kerala chief minister Pinarayi Vijayan said he was in touch with his counterpart in Tamil Nadu and will ensure the best treatment to the injured. State transport minister AK Saseendran said all the injured will be brought to Kerala and the government will pay for their treatment.