From The TimeSplitters Wiki

Minigun Noise Glitch
Requirements	Minigun
Finder	Nevar00

If a player shooting the Minigun gets killed, the shooting sound may continue after the player's death. The Minigun sound will get stuck in the specific spot where the player with the Minigun died, so the closer you are to that spot, the louder the shooting sound is. The only way to turn off the sound is to end the match. A similar Glitch happens with the Lasergun.