Ashley Cole is alleged to have shot and wounded a work experience boy at the club.
The incident happened last Sunday at the Blues Cobham training ground when Cole pulled the deadly .22 air gun from a box and fired at 21-year-old student Tom Cowan from just FIVE feet away.
A source told the News of the World: "It's truly inconceivable that a Premier League footballer could bring a gun to the training ground.
"But Ashley pulled the rifle from a box and started larking about with it in the changing room, not realising it was loaded. It ended up pointed at Tom just five feet away.
"The gun went off with a loud pop and Tom screamed as this lead pellet hit him in the side. It went through his clothing and into his flesh."
Police were not called, but injured Tom was patched up by medics and given time off to recover.
Under British law Cole could be charged with actual bodily harm, which carries a maximum penalty of five years' imprisonment and an unlimited fine.