An overnight siege by SWAT officers ended Thursday morning when officers made entry to the second-story unit and discovered the bodies of a man and a woman inside.
It was not certain if the pair had committed suicide or had been injured in a flurry of gunfire late Wednesday night that cost the life of a veteran police officer and left a police dog wounded, police told KGTV-TV, San Diego.
KGTV said three other people were in custody, although their roles in the deadly standoff were not immediately known. The name of the slain officer, a 15-year veteran of the force, was not released.
The incident began when San Diego police and U.S. marshals went to the home to conduct a probation check on a resident. Shots flew as soon as the officers kicked in the door, forcing the officers to retreat with their wounded comrade, who died at a San Diego hospital.
Some of the officers were pinned down inside the apartment for a short time. One officer had to climb down a fire department ladder from a bedroom window, The San Diego Union-Tribune said.