Civilians took shelter on both sides of the border between Cambodia and Thailand on Monday, as clashes reignited between the two nations.

Fighting broke out following a skirmish in which one Thai soldier was killed Sunday night, despite a ceasefire that ended five days of fighting in July over competing territorial claims along their border, which resulted in dozens of civilian and military dead on both sides, and the evacuation of over 100,000 civilians.

Cambodia’s powerful Senate President Hun Sen on Tuesday vowed that his country would carry out a fierce fight against Thailand.