In the dark metros, it's not unusual for the infrastructure to give way and collapse seemingly at random. It wasn't as if anyone was going out of their way to ensure the structural integrity of these cement walls after years of relentless ice and snow. So for any experienced wandering, they should know the signs of collapsing walls. And Cat could tell that the explosion that rocked the drug store had suddenly turned the area into a danger zone. The walls were cracked, ice and water dripped from the ceiling. Another explosion like that would bring down the entire tunnel. And even now, this place might collapse anywhere between a few days to a few minutes. Cat needed to get out of here, fast.
Donny was just a few feet behind her, staggering. He made the rookie mistake of not covering up his ears or making sure his body was ready to adjust to the sudden shift in air pressure. Despite going only at a relatively mild jog, his head was suffering from some major ringing and his body felt like a mutant just smashed his chest. He was out of breath and feeling suddenly exhausted. When Cat went to him Donny tried to gather his breath but suddenly drew his pistol. He aimed it past Cat at something shambling down the hall. The movements were all too familiar: a ghoul. Brain-dead and partially frozen. Surely it couldn't have just arrived in this state, no so soon after the explosion. It must've been a lone wanderer. Or worse. A scout.
There were another tunnel to the left the duo could go down, leading deeper into the underground metro. Unknown to the duo, and the ice seemed undisturbed. Could be that no one else has been here in a while. Or, it's possible the ice has covered the trail of anyone who has been here. The existence of the ghoul shambler certainly showed that this area was not completely uninhabited, for better or for worse. "Gotta go. Kill or go?" Donny said between heavy breaths.