Police cars at the scene of the shooting.

The shooting came as departments around the country are on high alert following the killing of officers in Dallas and Baton Rouge, Louisiana, this month. San Diego Police Chief Shelley Zimmerman said it was unknown whether the San Diego attack was premeditated. The chain of events unfolded over more than 12 hours in a blue-collar area of southeastern San Diego with modest single-story homes and streets lined with palm trees.

San Diego Police SWAT officers when they prepared to enter house with a possible suspect inside. Picture: AP/Denis PoroySource:AP

It started about 11pm local time on Thursday when two veteran gang unit officers in bulletproof vests stopped a person on a street. Almost immediately a shootout ensued and the officers called for backup. Authorities initially said the officers made a traffic stop involving a motorist, but clarified later that they were still trying to determine whether it was a traffic stop or a stop to check out a pedestrian.

San Diego Police officer Wade Irwin, a nine-year veteran who was wounded in a shooting. Picture: San Diego Police Department via APSource:AP

San Diego Police officer Jonathan DeGuzman who was killed in a shooting. Picture: San Diego Police Department via APSource:AP

“It happened extremely quickly,” Police Chief Shelley Zimmerman said.

“From the information that was put out that a stop was being made to that the officers called for emergency cover to when the other officers arrived on scene, we’re talking very, very quickly. Seconds to a minute or so.”

Jonathan DeGuzman, a 16-year veteran of the force who was married with two children, suffered multiple gunshot wounds. The 43-year-old died at Scripps Mercy Hospital after doctors’ efforts to save him failed.

Wade Irwin, 32, underwent surgery after being shot and was expected to survive, Zimmerman said. His wife was at his side during surgery.

Police swarmed the neighbourhood where the shootout happened and quickly captured 52-year-old Jesse Gomez in a nearby ravine, Zimmerman said. He was in critical condition on Friday with a gunshot wound but was expected to survive. Police gave no further information about Gomez or his role in the shootout except to say he was a suspect.

During the search for a second man described as a “potential” suspect, residents were ordered to stay in their homes throughout the night as San Diego police and officers from other law enforcement agencies scoured yards, streets and alleys. A helicopter hovered over the neighbourhood.

About nine hours after the shootout, heavily armed officers surrounded a house about 1 kilometre away, one of them using a loudspeaker to urge a man to surrender. Authorities also detonated several devices at the scene to draw him out and used tools to break windows and pound on the roof.

Then, about a dozen heavily armed SWAT officers raced to another house about two blocks away, positioning an armoured truck and robots outside. The possible suspect wasn’t there either.

Zimmerman said late on Friday afternoon that officers arrested a man on an unrelated warrant outside the first home surrounded by SWAT officers.

A suspect in the police shooting was wounded and taken into custody while another was arrested outside a home SWAT teams had surrounded. Picture: AP/Denis PoroySource:AP

She said police were investigating to see whether 41-year-old Marcus Antonio Cassani had any role in the police shootings. After visiting Irwin at UC San Diego Medical Center early Friday, Zimmerman told reporters that the officer’s prospects for recovery were good. The nine-year veteran of the force had just joined the gang unit in June.

“It’s a little bit of a long haul until he makes a full recovery, but the good news is that he is going to survive and he is going to recover,” she said.

San Diego Police Chief Shelley Zimmerman said she knew the slain officer well. Picture: John Gastaldo/The San Diego Union-Tribune via APSource:AP

Earlier, Zimmerman told reporters she knew DeGuzman well.

“I can tell you he is a loving, caring husband, father. Talked about his family all the time,” Zimmerman said.

“I know him, and this is gut-wrenching. He cared. He came to work every single day wanting to just make a positive difference in the lives of our community and that’s why he lost his life.” DeGuzman received the purple heart in 2003 after he was stabbed by a man he had stopped for speeding. The man was convicted of attempted murder on a peace officer in 2004.

San Diego Mayor Kevin Faulconer denounced the shootings.

“I ask all San Diegans and all people across our nation to join together in support of our officers who courageously protect our communities,” he said. “We need them and they need us.”