After hearing explosions they are a

After hearing explosions they are attacked by masses of zombies.

Results (Chinese) 1:

在听到爆炸声后，他们受到攻击，大量的僵尸。

Results (Chinese) 2:

听到爆炸后，他们被群众僵尸的攻击。

Results (Chinese) 3:

听到爆炸后被僵尸袭击群众。