Simplify the following text for a Grade 5 native English-speaking person.
Original: Thick smoke had filled the room from so many weapons being fired at close quarters , as well as from plaster dust released from the walls by bullets . To allow the haze to clear , the gunmen left the room for some minutes , leaving all the victims behind .
Simplified: Thick smoke and dust filled the room from the shooting , so the gunmen left the room for a few minutes .