At about 1:30am, the vanguard of the 38th Army from the XV Airborne Corps arrived at the north and south ends of the Square, respectively. They began to seal off the Square from reinforcements of students and residents, killing more demonstrators who were trying to enter the Square. Meanwhile, the 27th and 65th Armies poured out of the Great Hall of the People to the west and the 24th Army emerged from behind the History Museum to the east. The remaining students, numbering several thousand, were completely surrounded at the Monument of the People's Heroes in the center of the Square. At 2am, the troops fired shots over the heads of the students at the Monument. The students broadcast pleadings back toward the troops: "We entreat you in peace, for democracy and freedom of the motherland, for strength and prosperity of the Chinese nation, please comply with the will of the people and refrain from using force against peaceful student demonstrators." At about 2:30am, several workers near the Monument emerged with a machine gun they had captured from the troops and vowed to take revenge. They were persuaded to give up the weapon by Hou Dejian. The workers also handed over an assault rifle without ammunition, which Liu Xiaobo smashed against the marble railings of the Monument. Shao Jiang, a student who had witnessed the killings at Muxidi, pleaded with the older intellectuals to retreat, saying too many lives had been lost. Initially, Liu Xiaobo was reluctant, but eventually joined Zhou Duo, Gao Xin and Hou Dejian in making the case to the student leaders for a withdrawal. Chai Ling, Li Lu and Feng Congde initially rejected the idea of withdrawal. At 3:30am, at the suggestion of two doctors in the Red Cross camp, Hou Dejian and Zhuo Tuo agreed to try to negotiate with the soldiers. They rode in an ambulance to the northeast corner of the Square and spoke with Ji Xinguo, the political commissar of the 38th Army's 336th Regiment, who relayed the request to command headquarters, which agreed to grant safe passage for the students to the southeast. The commissar told Hou, "it would be a tremendous accomplishment, if you can persuade the students to leave the Square. At 4am, the lights on the Square suddenly turned off, and the government's loudspeaker announced: "Clearance of the Square begins now. We agree with the students' request to clear the Square." The students sang "The Internationale" and braced for a last stand.