Nice use of selective quoting, the situation had already escalated at that point. From your source, one paragraph before yours:

The advance of the army was again halted by another blockade at Muxidi, about 5 km west of the square. After protesters repelled an attempt by an anti-riot brigade to storm the bridge, regular troops advanced on the crowd and turned their weapons on them. Soldiers alternated between shooting into the air and firing directly at protesters. Soldiers raked apartment buildings with gunfire, and some people inside or on their balconies were shot.

And, from the beginning of the section:

At 9:30 p.m, this army encountered a blockade set up by protesters at Gongzhufen in Haidian District, and made an attempt to break through. Troops armed with anti-riot gear clashed with the protesters and began firing rubber bullets and tear gas, while the protesters in return threw rocks and soda bottles at them. Other troops fired warning shots into the air, which was ineffective.