SKAGIT COUNTY, Wash. -- A total of eight people have been shot and six, including a sheriff's deputy, have died in a rampage northeast of Seattle.

During a press conference, Washington State Patrol Trooper Keith Leary that the rampage had officers and deputies investigating at seven different crime scenes in Skagit County, Wash.

TV station KIRO 7 reported that the slain sheriff's deputy was responding to a disturbance call at about 2:20 p.m. When the sheriff's deputy arrived, one person was already dead in the home, Leary said.

Some time went by before the police station called the officer to do a status check. When they received no answer, police responded to the sheriff’s deputy and found him fatally shot in the head, Skagit County police said.

Two construction workers were found fatally shot at a nearby home under construction, and a fourth victim was found dead at another home in the same area, Leary said.

At some point, a customer at a Shell gas station in Alger was also shot in the arm. A clerk at the gas station told KIRO 7 that she was in the cooler when she heard commotion outside the station. The clerk said a man was firing his gun and hit a customer.

Once authorities caught up with the gunman, a high-speed pursuit ensued and reached speeds of 90 mph as southbound on Interstate 5 near Mount Vernon shortly after 4 p.m.

As he fled, the gunman also shot and killed a motorcyclist who was pulled over on the shoulder, Leary said. Also during the chase, a Washington State Patrol trooper was shot in the arm -- he was hospitalized with non-life-threatening injuries.

The pursuit ended when the suspect drove to Mount Vernon, Wash., precinct of the Skagit County Sheriff’s Office and surrendered, Leary said. A bullet hole was found in the passenger side window of the suspect's truck, reported KIRO 7 Eyewitness News.

Police said the accused gunman is known for having mental health issues and that he had been on a Mount Vernon watch list. Police said they believe the he is responsible for all eight shootings, and are interviewing to find out a motive.

A woman who identified herself as the gunman's mother said she has tried for years to get mental help for her son.

"When they’re over 18, you can’t make them go anywhere," said Dennise Zamora, a woman who identified herself as the suspect’s mother. "He just turned 28."

"Those people, those precious people and that officer," Zamora said. "This is the truth: I love him, but I would of rather it would have been him than any of them. It’s not his fault that he is mentally ill."

Zamora said she said she doesn’t know what might have triggered the shooting rampage.