(CNN) A Birmingham, Alabama, police officer radioed for help, with the sound of gunfire in the background. His chief says it was a hoax and an attempt at "stolen valor."

Officer Keith Buchanan was arrested Thursday after police said he faked a call for help and injuries while on duty last month. Birmingham Police said he was charged with false reporting, criminal mischief and discharging a firearm in city limits.

Buchanan had already been relieved of duty, Police Chief Patrick Smith said, and every case he handled is now under review.

The officer was patrolling a rural road near Tarrant about 1 a.m. July 21. He radioed in to report that he was making a traffic stop, CNN affiliate WVTM reported.

Then, "Buchanan put out a help call with shots being fired in the background," Smith said Thursday. "For approximately 30 minutes, our communications dispatchers were unable to reach him."

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