Passage: At dawn on 6 October, the military and the police as well as the three paramilitary forces blocked exits from the university and began shooting into the campus, using M-16s, carbines, pistols, grenade launchers, and even armor-piercing recoilless rifles. Prevented from leaving the campus or even sending wounded to the hospital, the students begged for a ceasefire. The attacks continued. The actors in the mock hanging had already turned themselves in to Seni at the prime minister's office. When one student came out to surrender, he was shot and killed. After a free-fire order was issued by the Bangkok police chief, the campus was stormed, with Border Patrol Police  leading the attack. Students diving into the Chao Phraya River were shot at by naval vessels while others who surrendered, lying down on the ground, were picked up and beaten, many to death. Some were hung from trees and beaten, others were set afire. Female students were raped, alive and dead, by police and Red Gaurs. The massacre continued for several hours, and was only halted at noon by a rainstorm.

Question: How long did the massacre lasted?
several hours