(NEW YORK) -- Police are investigating multiple separate shootings that occurred Monday night on Interstate 5 in Washington state in what authorities called unacceptable "mayhem."
Six people were injured in six shooting incidents, including a woman who was critically injured, according to the Washington State Patrol.
A suspect whose vehicle was sought in connection with several of the shootings was arrested in the Tacoma area early Tuesday, police said.
In four of the incidents, the victims reported being shot at by a white Volvo, according to Washington State Patrol spokesperson Chris Loftis. Investigators are still working to determine whether all the shooting incidents involved the same suspect vehicle, according to Capt. Ron Mead, the commander of District 2 of the Washington State Patrol, located in King County.
Police are treating this as a mass shooting event, Loftis said.
"The only difference from this and other events that we see across the country in schools and parks and so forth is the area of the shooting was not confined to a very specific place or location," Loftis told reporters during a press briefing Tuesday afternoon.
There were two "spasms" of violence along I-5, resulting in the six shooting incidents, Loftis said.
The first occurred over 17 minutes, between 8:26 and 8:43 p.m. local time, northbound on I-5, he said.
It unfolded at I-5 and State Road 18, when "several rounds" were fired from a white Volvo, striking the passenger of a car, Loftis said. The driver took the 320th Street exit and contacted a fire station, and the female passenger was transported to a local hospital, where she remains in critical condition, he said.
A few minutes later, at 8:42 p.m. local time, a victim reported being shot at on I-5 near Martin Luther King Jr. Way and sustained abrasions from broken glass, Loftis said. The victim did not have a description of the suspect vehicle.
One minute later, on I-5 just south of I-90, a victim reported being shot at by an unknown vehicle and sustaining a grazing wound to the leg, Loftis said. The victim was transported to a local hospital as a precaution, he said.
The second wave of gun violence occurred between 10:57 p.m. and 11:01 p.m. local time, southbound on I-5, Loftis said.
On I-5 at State Road 18 at 10:57 p.m., a driver and passenger reported being shot at by a white Volvo, Loftis said. They sustained non-life-threatening wounds to the legs and have since been released from the hospital, Loftis said.
One minute later, another shooting involving a white Volvo was reported on I-5 near South 375 Street, Loftis said. Windows in the car were broken, but no one was injured, he said.
Then, at 11:01 p.m., on I-5 near 54th Avenue, a victim reported being shot by a white Volvo, Loftis said. The victim was shot in the neck and transported to a local hospital, he said.
A suspect was subsequently identified and arrested in the Tacoma area, police said.
Pierce County sheriff's deputies arrived at the home of the possible suspect late Monday, but his vehicle wasn't there, the Pierce County Sheriff's Department said.
Shortly after midnight on Tuesday, a deputy saw the suspect vehicle pull into an apartment complex, the sheriff's department said. Backup arrived, and deputies followed the vehicle, which was subsequently disabled by stop sticks set up by a Fircrest police officer, authorities said.
"Once the vehicle ran over the sticks it came to a stop and deputies initiated a felony stop," the Pierce County Sheriff's Department said in a press release. "The suspect was compliant and taken into custody by a Fircrest officer and WSP trooper."
The suspect has been booked into King County Jail on first-degree assault, police said.
State police said they are not releasing the name of the suspect at this time or speaking to an alleged motive.
"I'm not going to give that credibility for the mayhem he created," Mead told reporters.
All of the victims are believed to have been random in what Mead called an "unwarranted, unprovoked attack."
"Any one of us could have been that unwitting victim," he said while decrying the gun violence.
Police said there may be additional victims. A person who was traveling on I-5 to Portland Monday night called police Tuesday to report that their car had been shot, Loftis said.
"They heard the news accounts and realized that they may have been involved in this situation," he said.
No one was injured in that incident. The person is in the process of traveling to Bellevue to speak with detectives to determine if this is a potential seventh victim of the shooting spate, Loftis said.
"We would like to encourage other folks who may have been in this area last night during these timeframes, if you saw something, call," he said.
At this time, police said they can only connect the shootings in which the victims reported seeing the white Volvo, Mead said.
"While the timing certainly would suggest that all of these are related, we're only going to be able to connect what we can connect through physical evidence," he said. "Beyond that is speculative, and that's why we will do the investigation to make sure that we can tie them to the additional shootings."