ALGER, Wash. (AP) – Authorities on Wednesday were trying to determine what set off a shooting and stabbing rampage that left six people dead and four wounded, attacks they blame on a drug offender who was released from jail less than a month ago.

The mother of suspect Isaac Zamora said he is “desperately mentally ill” and had been living in the woods. Dennise Zamora said one of those killed Tuesday was a sheriff’s deputy who had tried to help their family for years.

Isaac Zamora, 28, was charged Wednesday in Skagit County District Court with two counts of attempted first-degree murder; police Sgt. Robert Goetz said he expected more charges would be filed as the investigation continued. Bail was set at $5 million.

The shootings began close to Dennise Zamora’s house near the small town of Alger, about 70 miles north of Seattle. They continued amid a high-speed police pursuit on Interstate 5 and ended in Mount Vernon, about 20 miles south of Alger, when Isaac Zamora turned himself in at a sheriff’s office.

The dead included two construction workers killed in Alger and a motorist shot along I-5 near a rest stop.

“Some of these are just random shootings,” Trooper Keith Leary said.

A host of questions remained unanswered Wednesday, including whether the suspect knew any of the victims, how the shootings apparently continued during the police chase and how Zamora managed to turn himself in rather than being arrested by one of the many officers pursuing him.

There are eight crime scenes, which are being investigated by more than 100 people from 15 different agencies, Leary said Wednesday.

“We’re not speculating as to what happened,” Leary said. “It’s too early to tell what took place at each scene.”

Zamora had just served a six-month jail sentence for drug possession in Skagit County.

“We’re so devastated for the families,” Dennise Zamora told The Associated Press by telephone. “I wish it would have been him or me that was killed. That’s how deeply I feel about it.”

She said she wanted people to know that “my son was desperately mentally ill and we’ve been trying to get him help.”

She told The Seattle Times that her son had lived in the woods off and on for years, was unaware of his mental illness and resisted all efforts to get him to accept treatment. The nature of his illness was not immediately clear, but his mother told the newspaper her son had struggled with it since the family’s house burned down more than a decade ago.

She said Zamora was “agreeable” and “placid” Tuesday morning and that she didn’t know what made him change. She also said she didn’t know where he got the gun used in the shootings.

The six who died included Skagit County Sheriff’s Deputy Anne Jackson, 40, who was shot while responding to a call from Dennise Zamora. The mother told The Times she called Jackson after seeing her son going into and out of her neighbors’ homes.

Dennise Zamora described Jackson as a sympathetic figure who had tried to help the family in the past.

“She was very gracious,” she said. “She knew exactly what we were going through, said her brother was going through some similar stuff.”

The first shootings were reported shortly after 2 p.m. Tuesday and the suspect was in custody at the Skagit County Sheriff’s Office by about 4:30 p.m.

Jackson and a second person were killed at the same location near Alger, two construction workers were found shot nearby, and a body was found a few houses away, Leary said.

A 56-year-old man was shot and wounded in the Alger area, and a 61-year-old man was stabbed in the chest, said Everett police Sgt. Robert Goetz, who was speaking on behalf of a multi-agency response team. Information on the men’s conditions had not been released Wednesday.

From the Alger area, the armed man raced south on Interstate 5 at speeds in excess of 90 mph, with troopers, sheriff’s deputies and Mount Vernon police in pursuit, Leary said. It was not immediately clear if Zamora had been shooting as he drove, or if he had pulled over and started firing.

At least two others were wounded, including a Washington State Patrol trooper shot while trying to stop the shooter on the freeway, the State Patrol said. A motorcyclist was shot in the arm at a Shell gas station.

The wounded trooper drove himself to a hospital and was released after treatment. He was identified as Trooper Troy Giddings. Names of other victims have not been released.

Since his Aug. 6 release, Zamora had reported as ordered to corrections officials and had passed drug and alcohol screenings, Corrections Secretary Eldon Vail said.

“I want to extend our profound sorrow and heartfelt sympathy for the victims of the shootings,” Vail said. “This is a senseless loss of the lives of innocent citizens and a member of our law-enforcement family.”

Gov. Chris Gregoire called for an independent third-party review to be led by the head of the Washington Association of Sheriffs and Police Chiefs and a prosecutor to be appointed by the Washington Association of Prosecuting Attorneys.

“I will be directing them to look into how this case was handled and provide an initial report to me within 10 days,” Gregoire said late Tuesday night.

Hours after the shootings, a group of residents gathered at the Alger Bar and Grill.

“It’s devastating for this town,” Steve Thomas said, “The people here are very law enforcement-friendly. It’s very somber.”