(KRON) — An arsonist who used flares to ignite a brush fire in Vallejo on Saturday was detained by a witness who was a “trained mixed martial artist” and later arrested, according to the Vallejo Fire Department. The three-alarm fire broke out shortly before 7 p.m. Saturday near the intersection of Admiral Callaghan Lane and Turner Parkway.

Fire crews cleared the scene of an earlier structure fire in east Vallejo to respond to the incident. Vallejo FD described the blaze as a “fast moving fire” that was burning through a mowed field, driven by 15-20 mph winds.

“A total of 3 alarms were struck in order to provide adequate resources,” the fire department said.

The fire burned about 15 acres and was brought under control by 7:48 p.m.

According to Vallejo FD, “a vigilant Vallejo citizen observed a man deliberately starting a vegetation fire with a flare.” The witness then followed the arsonist as he ran across the street and got into a black Tesla parked nearby.

Before the suspect could drive away, the witness “removed him from the vehicle” and “introduced him to a double armbar,” according to Vallejo FD. The arsonist remained submitted in the double armbar until police arrived and arrested him.

Police were able to confirm the arsonist started the fire through witness testimony and surveillance footage. After being advised of his Miranda Rights, the arsonist admitted to starting the fire, and to stealing the Tesla he tried to escape in. Vallejo PD discovered the car had been stolen in Fremont.

The fire is under investigation and is being treated as arson, Vallejo FD said.

KRON On is streaming live news now

Mutual aid was provided by Fairfield, Benicia, Suisun, Crockett, American Canyon and Cal Fire.