New Delhi, July 25 -- Armed clashes have broken out between Thailand and Cambodia in long-disputed border areas, rapidly escalating months-long tensions.

The fighting included gunfire exchanges and shelling and rocket fire, which Thai authorities said killed a Thai soldier and 13 civilians and wounded 14 soldiers and 32 other civilians. Thailand responded with air strikes.

It was the second armed confrontation since a Cambodian soldier was shot dead in May and a major escalation that came hours after the two countries downgraded diplomatic relations following a land mine explosion that injured Thai soldiers.

Clashes are ongoing in at least six areas along the border, the Thai Defense Ministry said. The first clash Thursday morning happ...