Los Angeles school police officer who said he was shot by an attacker last week, prompting a manhunt that shut down a large swath of Woodland Hills, has been arrested on suspicion of concocting the story, authorities said Thursday night.

The startling revelation came at a hastily called news conference by Los Angeles Police Chief Charlie Beck, who said detectives became suspicious about the officer's story as they investigated the case.

A terse Beck said Los Angeles School Police Department Officer Jeff Stenroos had been booked on a felony charge of filing a false police report. He declined to elaborate further on the case, which the head of the Los Angeles Police Protective League called an "embarrassment to law enforcement."

Police had said Stenroos was shot in the chest Jan. 19 after he confronted a man who was attempting to break into vehicles near the eastern boundary of the El Camino Real High School campus. Stenroos' bulletproof vest absorbed the impact of a single gunshot, which Los Angeles Police Department officials said could easily have killed the officer.

The incident sparked a massive police response that inconvenienced thousands of people for the day as officers blocked roads, locked down schools and refused to let people in or out of a 7-square-mile area.

Authorities arrested Stenroos after he allegedly admitted to fabricating the story, a senior LAPD official close to the investigation told The Times.

The official said investigators were still piecing together how Stenroos had pulled off the hoax.

But the source added that Stenroos' protective vest showed obvious signs of having been struck by the bullet. Stenroos suffered bruising to his chest, raising questions for detectives about whether the officer shot himself accidentally and then fabricated a story or concocted the whole scenario. The source declined to say whether additional arrests would be made in the case.

"Obviously it's as shocking to us as it is to anyone else," Steven Zipperman, chief of the Los Angeles School Police Department, said late Thursday.

Zipperman, a former LAPD captain, said his department was cooperating fully with the investigation.

Paul M. Weber, president of the Los Angeles Police Protective League, said Stenroos was a "disgrace."

"The law enforcement community is disgusted," Weber said in a statement. "While Mr. Stenroos is a disgrace to the badge, his individual and dangerous actions should not reflect on the hard-working men and women in law enforcement."

More than 300 officers swarmed the west San Fernando Valley in search of a gunman, locking down nine schools and setting up a dragnet as they looked for a suspect described as a white man in his 40s, wearing a bomber or black-hooded jacket and blue jeans.

Although many in the community expressed frustration and anger at the inconvenience caused by the size and length of the operation, LAPD officials defended the decision as necessary to protect the public from a suspect who was believed to have shot an armed officer. They noted that the incident was especially serious because it involved an attack against a fellow law enforcement officer.

Stenroos said he was knocked back and hit his head. Coast Guard Auxiliary member Michael Brodey found Stenroos and immediately summoned help using the officer's police radio while providing aid. Brodey did not report seeing a gunman.

Authorities offered a $100,000 reward for information in the case and even distributed a composite of the suspected gunman.