A Thai fighter jet dropped bombs on Cambodian military targets along their disputed border on Thursday, as armed clashes between the two Southeast Asian neighbors killed at least 11 civilians, in a dramatic escalation of tensions that threatens to erupt into a broader conflict.

Both sides have accused each other of firing the first shot as border tensions between the two South East Asian neighbours heat up.

Thailand and Cambodia were engaged in armed clashes, including rocket and artillery fire, along a disputed area of their border, the U.S. State Department said in an alert. Both countries accused the other of firing the first shots as tensions boiled over on Thursday and reports of casualties begin to emerge.