SACRAMENTO, Calif. — More than 100 law enforcement officers from across Northern California responded without being asked after hearing that one of their own had been killed at the start of a shooting rampage.

Federal, state and local officers eventually swarmed across a 30-mile region encompassing two counties, Placer County sheriff’s spokeswoman Dena Erwin said.

“We don’t call for those people,” Erwin said. “They just show up on their own because they know a fellow officer has been shot.”

The officers from the state Department of Justice, FBI, U.S. Department of Homeland Security and other agencies will be questioned as part of the investigation into the attack on Friday that ended after two deputies were dead and two other victims were wounded.

Two suspects were questioned for hours as authorities sought a motive for the shootings that began when Sacramento County sheriff’s Deputy Danny Oliver, 47, was shot in the forehead with an assault rifle at close range as he checked out a suspicious car in a motel parking lot.

Deputies suspect the shooter was 34-year-old Marcelo Marquez of Salt Lake City, who was being held without bail on suspicion of two counts of murder, two counts of attempted murder and two counts of carjacking.

A woman with him, 38-year-old Janelle Marquez Monroy, was in custody on suspicion of attempted murder and two counts of carjacking.