It was not immediately clear if the clash was ongoing. A livestream video from Thailand's side showed people running from their homes and hiding in a concrete bunker Thursday morning as explosions sounded periodically.

Fight erupted near the centuries-old Prasat Ta Muen Thom temple, which straddles the border between Thailand’s Surin province and Cambodia’s Oddar Meanchey province, adding a historical dimension to the ongoing territorial conflict

Thailand and Cambodia blamed the other for initiating the gunfire. The confrontation came after Cambodia declared a downgrade in diplomatic ties with Thailand and ordered the withdrawal of all its embassy staff from Bangkok.

Cambodia’s action was a response to Thailand’s earlier decision to shut down border crossings in the northeast, recall its ambassador, and expel Cambodia’s envoy following a land mine blast that wounded five Thai soldiers.

Relations between the Southeast Asian neighbours have deteriorated sharply since May when a Cambodian soldier was killed in an armed confrontation in another of the several small patches of land both countries claim as their own territory.