The gunman, identified by sheriff's officials as 27-year-old Trenton Trevon Lovell, a Lancaster resident, was being held without bail.
Sgt. Steve Owen and another deputy had responded to a burglary call around noon Wednesday in the 3200 block of West Avenue J7, sheriff's officials said. The area was contained and during the containment, gunfire was heard in the back of the location.
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According to McDonnell, Lovell immediately approached Owen and shot him. Lovell then stood over Owen and shot him four more times, McDonnell stated.
"When you look at what we know at this point, this was a calculated execution," McDonnell said.
The deputy at the front of the complex ran in the direction of the gunfire and found Owen suffering from gunshot wounds. McDonnell said the deputy who found Owen fired at Lovell several times, striking him once in the shoulder.
Lovell then fled the area on foot, ran to the front of the home and attempted to steal Owen's patrol car, according to authorities.
Lovell put the car into reverse, ramming the second patrol car, which resulted in a second deputy-involved shooting, authorities said.
Authorities said Lovell then fled from the area on foot and ran into another home with two teens inside. Special Enforcement Bureau officers were able to get the teens safely out of the home before Lovell was taken into custody.
McDonnell said Lovell had a lengthy criminal record beginning as a teenager, and included 11 arrest, two stints in state prison and stated he was on parole at the time of the shooting.
Capt. Steven Katz said the sergeant was a prolific member of the department.
"It's a very difficult time, as you can imagine, for the many members of our department. We're all suffering," he said.
Owen was a Meritorious Conduct Medal, Gold recipient and his wife was a sheriff's arson explosives unit detective. Katz said that Owen's wife, his adult son and daughter, and his mother were able to see him in the hospital before he died.
"The sergeant's family is devastated. This is an individual that no matter who you talk to in the department, no matter who you talk to in the community, he was a larger than life person," McDonnell said. "He's somebody who was the epitome of what it is to be a peace officer."
Owen's body was transported to the coroner's office Wednesday night with a procession of patrol cars following close behind. First responders flashed their lights from overpasses as the sergeant's body passed.
Residents also lined the streets, some waving flags as the motorcade drove by.
Dozens of residents and deputies also attended a vigil outside the sheriff's station in Lancaster, where they held hands, sang and prayed together. A memorial of flowers, candles, flags and balloons continues to grow at the location.
A GoFundMe page has been established to help Owen's family.
Friends said Owen proved negative stereotypes of law enforcement wrong everyday with his actions.
"He did the absolute best that anybody could do to try to reverse what at least our community thought of law enforcement," Anthony Cheval, a friend of Owen said. "Owen worried about us all, no matter who you were, what color you were, where you came from, how rich or poor you were, it didn't matter to him. He helped you. If he could help you he would."
"Thank you to the men, women and children who described in great detail the inspired conversations they had with Sgt. Owen. They were saying that on their worst day he helped them believe that tomorrow would be a better one," McDonnell said.
For many in the community, Owen's death is a grim reminder of the dangers of the job.
"All life matters, not blacks, not Hispanics, all lives matter. Blue lives matter, they take care of the community," said Alberto Coredo, an area resident. "A tragedy like this shouldn't happen."
Owen served the department for 29 years and had spent the last five years at the Lancaster station. Flags flew at half-staff at the Lancaster sheriff's station in Owen's honor on Thursday.
Thursday night, deputies lined up outside the coroner's office in Boyle Heights and saluted Owen's flag-draped casket as it was loaded into a hearse.
His body was then escorted by a procession of deputies up the freeway to a Lancaster mortuary. Hundreds of people lined the streets in Lancaster to honor Owen's sacrifice and service.