KATHMANDU - An ill-fated bus veered off a mountain road and plunged into river late Sunday night killing at least 15 and injuring 25 in Palpa of West Nepal, some 200 kms from Kathmandu, police said.

The bus plated Lu-1-Kha was returning from a wedding ceremony and was carrying bride, groom and others. Twelve died on the spot, while three died in a hospital during treatment.

"We received information very late. Therefore, rescue could not be done immediately," said Surya Bahadur Chand, a police officer in Palpa.

The bus plunged some 300 meters down from the unfenced hilly road into Muslang river.

"The reasons for the incident have not been known yet. We are investigating the matter," the officer added. The bride and groom are injured and are undergoing treatment in two local hospitals along with other 25 wounded.

Nepal's mountainous roads are highly prone to accidents, as most of them are constructed without a complete and concrete fencing.

In a mountain road of Nepal, generally there is a natural hill-wall on one side, while on the other, there is an open downward slope leading into dangerous rivers.