If Ryan really was here, and he truly resembled Walton's description, then he certainly couldn't escape.
Two teams, led personally by the captain, headed to the roof: one took the elevator while the other climbed the emergency stairwell.
The apartment's lobby was small, and so was the elevator area. There used to be an apartment manager, but now the manager had already run outside.
The entrance to the rooftop was through the emergency passage, simply taking the emergency stairs directly up, which were typically accessible.
Gao Guang stood at the entrance of the apartment, watching the two elevators, noting one of them go from the first floor to the eighth, then stop there motionless.
No one was using the two elevators, unless someone started to evacuate the residents of this apartment building, and considering that the sniper was already dead, the next step would be to evacuate the crowd.