A Los Angeles County deputy lied when he said he was shot in the shoulder while standing in a car park at a sheriff’s station last week and will now face a criminal investigation, authorities have said.

“The reported sniper assault was fabricated” by Deputy Angel Reinosa, assistant sheriff Robin Limon said at a news conference.

Reinosa, 21, made a frantic radio call on Wednesday claiming he’d been shot by someone in a nearby building as he walked to his car outside the Lancaster station, prompting a huge police response.

Deputies set up a cordon and officers searched inside a sprawling building complex to search for the gunman.

At the time, investigators believed Reinosa’s bulletproof vest saved his life as a bullet grazed him.

A department statement the next day said a single round hit the top of Reinosa’s shoulder, damaging his uniform shirt but failing to penetrate his flesh.

But no bullets were recovered from the scene and detectives saw “no visible injuries,” Captain Kent Wegener said on Saturday night.

Much of the young deputy’s statement “was self-serving and didn’t make a whole lot of sense,” Mr Wegener said.

“There were many things that didn’t add up.”

Reinosa eventually admitted making up the story and using a knife to cut the two holes in his shirt, Mr Wegener added.

Reinosa has been relieved of his duties and could face charges for filing a false report about a crime, officials said. He did not explain his motive for the fabrication.

Reinosa had been with the LA County Sheriff’s Department for a year and joined the Lancaster station in May for patrol training.

Lancaster mayor Rex Parris told the Los Angeles Times on Sunday that sheriff’s officials had told him that Reinosa had been struggling in his probationary training period and “was not advancing through the training program at an adequate pace”.