A carjacker who authorities say carried a fake badge and impersonated a police officer was arrested in Santa Clarita on Tuesday after a homeless man chased and tackled him, according to the Los Angeles County Sheriff’s Department.

The unusual episode started with a carjacking in Bell Gardens, said Shirley Miller, a spokeswoman for the sheriff’s Santa Clarita Valley station.

A woman had listed her white pickup for sale and went to meet a potential buyer in that city. Miller said a man showed up in a black shirt that read “Police K-9 Unit” and went with the woman for what he said was a test drive — but ended up stealing the truck.

https://twitter.com/SCVSHERIFF/status/897614786200051713

The woman later saw what she believed to be her truck listed for sale on Craigslist, Miller said. She responded to the ad and said she was interested in the vehicle and agreed to meet the man in a shopping center parking lot on Soledad Canyon Road in Canyon Country.

When the man appeared around 5 p.m. Tuesday, the woman verified that it was her stolen truck and that the man who met her was the same man who had carjacked her. She then called 911, Miller said.

The man was wearing the same police shirt, Miller said.

When sheriff’s deputies arrived, the man took off running. A homeless man then chased the man, tackled him and held him down until deputies could handcuff him, Miller said. The suspect was carrying a fake police badge.

The homeless man is regularly in the area and was known to the deputies, who were grateful for his help, Miller said.

“The watch commander said to the deputies, ‘Make sure you offer him something to eat,’ ” Miller said. “We appreciate the brave, courageous efforts of this local citizen.”

Miller said this case stood out.

“The situation kept changing, and there was this little turn and that little turn,” she said. “Sometimes, the truth absolutely is stranger than fiction.”

In social media posts from the Santa Clarita sheriff’s station, the case was described with frequent capital letters and exclamation points.

“ALLEGED CARJACKER CAPTURED (with some help!)” the station wrote on Facebook. The suspect “took off running. But then...a citizen caught up to him and TACKLED HIM!! Suspect in custody!!”

hailey.branson@latimes.com

Twitter: @haileybranson

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