UPDATE: Associated Press is reporting that at least 30 people died in Monday’s accident:

BANGKOK (AP) — Officials say a double-decker bus carrying municipal workers on a field trip plunged off a steep road into a ravine in western Thailand, killing at least 30 people.

Tak provincial governor Suriya Prasatbunditya said Tuesday another 22 people were injured by the crash that occurred when the driver tried to pass other cars on a steep, winding mountain road.

The bus slid off the mountain road and then flipped several times before crashing into a tree. The driver told authorities the brakes stopped working.

The bus was one of four carrying local workers and villagers Monday night from Tak to northeastern Thailand.

The governor said more than 300 accidents took place last year on the winding, hilly road frequented by buses and trucks traveling across the border to Burma.

Earlier report:

At least 27 people died and 24 were injured Monday when bus plunged into a ravine in northern Thailand, AFP reports.

The victims are believed to be mostly local government officials who were on a field trip in Tak province, which borders Burma. Police said there were some children on the bus.

The accident took place at about 8.40pm local time. Police said that some of the survivors are in a very serious condition in hospital.

(MORE: Study: Thailand’s roads 2nd most dangerous in the world)

Thailand has one of the worst fatality rates in the world. In February, at least 13 school children died when their bus collided with a lorry on trip to the seaside south of Bangkok. In late December, 29 people died when a bus headed from Bangkok to Chiang Rai plunged over the side of a ravine.

Serious accidents like these are almost a monthly occurrence in Thailand, with sharp spikes in fatalities around the December and April holidays. Motorbike accidents are the most common cause of fatalities.