At least 18 migrant laborers sleeping beside a highway in the northern Indian state of Uttar Pradesh died after a truck crashed into a stationary bus early Wednesday.

At least 10 other people are reported to be injured and are currently undergoing treatment in the state's capital Lucknow. 

According to media reports, the workers had been traveling in the double-decker bus when its axle shaft broke close to the city of Barabanki. They then disembarked and were sleeping near the parked bus when the truck rammed into it from behind.

"The bus was overloaded and had about 150 passengers in it. It was hit by a truck on the highway," Barabanki police superintendent Yamuna Prasad told Reuters.

Most of the passengers were migrant workers returning home to the eastern state of Bihar after working in the states of Punjab or Haryana.

Some of the bodies were pulled from under the crushed bus. 

The district administration and the police have launched an investigation, police said. 

Prime Minister Narendra Modi offered condolences on Twitter to the families of the passengers who died in the accident.

"Deeply saddened by the news of road accident in Barabanki, UP. My condolences to the bereaved families," he wrote.

He added that arrangements were being made to ensure those with injuries received proper treatment.

dvv/nm (AFP, Reuters)