The black-clad men entered the Rattanaupap Temple in Narathiwat province near Malaysia Friday afternoon local time before firing the shots.
“Two monks were killed and two others were injured,” said the assistant Pakdi Preechachon.
Since 2004, clashes between Muslim, ethnic Malaysian rebels and the Buddhist majority have claimed 7,000 lives, mainly civilians from both sides. The dispute deals with lands that were annexed by Thailand a century ago.
The death toll last year was record low, after Thailand’s military junta raised security preparedness, but the violence has increased recently. Friday, four security guards were injured when two road bombs went off in the region. Last week, an imam was shot and killed in Narathiwat province.