BANGKOK, April 10 (Xinhua) -- At least six people, all Myanmar migrant workers, were killed and several others injured after a double-decker bus slid down into a roadside ravine in northern Thailand late Monday, Thailand's Department of Disaster Prevention and Mitigation said on Tuesday.

The accident happened at about 10:50 p.m. local time on Monday. The six Myanmar nationals were among a busload of 51 Myanmar migrant workers on their way from Mae Sot district of Tak province, about 420 km north of Bangkok, to Chachoengsao province in eastern Thailand where they had been employed, the department said.

Seventeen people, including one Thai and 16 Myanmar nationals were injured in the incident and were sent for treatment in a local hospital.

Meanwhile, Thai media Thairath said on Tuesday morning that 12 were killed and 18 were injured in the incident.

The police were looking into the double decker's conditions and its braking system.

Mae Sot is a main gateway between Thailand and Myanmar, through which many Myanmar migrant workers come to work in Thailand.

Thailand hosts some 3.8 million migrant workers from Myanmar, Cambodia and Laos.