At least four people have been killed and six injured in an attack in southern Thailand, according to police.

Four gunmen opened fire at a group of villagers paying respect to a Buddhist monk in Mae Lan district in Pattani province on Thursday, police Colonel Sathit Polpinit told the Associated Press news agency.

A 68-year-old monk, a woman and her 13-year-old son and another woman were killed in the Thursday morning attack, Polpinit said, adding that six others, including a police officer, were wounded.

It is the second time in three weeks that a Buddhist monk has been shot dead.

Police said the recent killings could be revenge attacks for the deaths of three young Muslim brothers.

Religious tensions

On Wednesday evening in Pattani's Yaring district, a 29-year-old Buddhist woman riding a motorcycle was shot dead and her body was set on fire, according to police.

A note left at the scene said: "To the army chief: this is not the last body for the three brothers."

The brothers, aged three, five and nine, were gunned down last week in front of their home in neighbouring Narathiwat province after returning from evening prayers at a mosque, according to AFP news agency.

More than 5,000 people have been killed in Thailand's Muslim-dominated southern provinces since 2004.

Police are still looking for the gunmen of Thursday's attack, who fled on two motorcycles.

Source: Agencies