Ba Chúc massacre () was a massacre carried out by the Liberation Army of Kampuchea (Khmer Rouge) from April 18 to April 30, 1978, in the town of Ba Chúc, An Giang Province, Vietnam killing 3,157 civilians. The Khmer Rouge army that invaded Vietnam took the local villagers to temples and schools to torture and kill them. The residents who fled to the mountains in the following days were also brutally slaughtered. Almost all the victims were shot, stabbed or beheaded. The event is considered to be the catalyst for the Vietnamese decision to invade Cambodia later that year, which would result in the ouster of both the Khmer Rouge and its leader Pol Pot. Background Communists in Vietnam and Cambodia allied to fight the U.S.-backed government during the Vietnam War, but after taking power the Khmer Rouge leadership began to purge its ranks of Vietnamese-trained personnel and then began to invade Vietnam. On May 3, 1975, the Khmer Rouge troops invaded Phu Quoc Island, then on May 10, they occupied Tho Chu Island, killing 528 civilians, and on June 14 they were expelled by the Vietnamese People's Army (PAVN). Despite the conflict, the leaders of the reunified Vietnam and Cambodia had several public diplomatic exchanges during 1976 to underscore their supposedly strong ties; however, the Khmer Rouge began cross border attacks. A cross border attack occurred in Kien Giang province on March 15–18, 1977 and in An Giang province from March 25 to 28, with more attacks on April 30, May 17 and May 19 killing 222 civilians, in the May 17 attack The Central Khmer Rouge shelled Chau Doc, the capital of An Giang Province. On September 25, 1977, during the Mid-Autumn Festival, the Khmer Rouge launched an attack along the Cambodia-Vietnam border, about 10 kilometers deep into the territory of Tay Ninh Province, killing 592 local residents. Massacre On 18 April 1978, the Liberation Army of Kampuchea crossed the border in Vietnam and surrounded the town of Ba Chúc from the border, cutting off all roads leading into the town. The Khmer Rouge then began to go from house to house looting valuables and killing cattle, before burning the houses to the ground. Any civilians that were caught by the Khmer Rouge soldiers were rounded up into schools and temples and killed with various melee weapons; civilians were shot and had their throats cut or were beaten