Tangyu followed the two men to the underground parking garage beneath the school building, where many students parked their bicycles. It seemed like a reasonable use of resources for each building to have its own parking space underground. The men didn't notice Tangyu as they reached the parking garage. One of them scanned the area, and after confirming their target, made a hand gesture to the other, indicating that all was OK.
The other man immediately opened the garbage truck, took out a time bomb, and found a hidden spot to install it. Seeing them set up a time bomb at the school shocked Tangyu; such ruthless thugs were planting explosives under a school building which, if detonated, would lead to unthinkable consequences. What massive scheme lay behind their actions? Tangyu scanned the surroundings and noticed several security cameras, yet these men were planting bombs unchecked, suggesting that they might have seized control of the school's security room as well.