Armed men purported to be from Burma killed a man and women and left a teenage girl injured after opening fire on a village in western Thailand, close to the Nupo refugee camp.

The men arrived at Pankhalae village on Tuesday evening and peppered a number of houses with bullets, residents said. The identity of the militants has not been confirmed, but Thai media reported they were from Burma.

A Thai couple died on the spot and a 14-year-old girl was taken to hospital in the border town of Mae Sot. Medics say she is in a stable condition. The motive behind the shootings is unclear.

Pankhalae resident Nai Chetchawan told reporters there were 10 to 15 armed men involved in the attack, and pools of blood were still visible yesterday where the three were shot.

Thai authorities have since tightened security around the village, which lies in Umphang district south of Mae Sot and which borders Burma.

Militants from Burma have been known to cross over the border to carry out operations in Thailand. In January 2010, members of the then-Burmese junta aligned Democratic Karen Buddhist Army (DKBA) shot a Thai village chief, leaving him seriously injured.

The porous border between the two countries is a source of concern for Thailand, particularly given the vast quantities of illegal drugs that flow in from Burma each year.