The search of neighborhoods north of the scenic Waldport Bridge included an Oregon State Police special weapons unit and officers from multiple law enforcement agencies.
Investigators have not identified the gunman.
They said they also were trying to locate David Anthony Durham, the registered owner of the 1984 Dodge truck driven during the attack in Lincoln City.
Durham, 43, lives on Sauvie Island in the Portland area and was described as a white male, about 6-foot-3 and 185 pounds.
Police said they released his name and photograph to help confirm he is safe and to interview him to learn if he has information to help identify and locate the suspect, said Lt. Gregg Hastings, a state police spokesman.
Officer Steven Dodds, 45, a six-year veteran of the Lincoln City Police Department, was in critical condition after undergoing surgery at Legacy Emanuel Hospital in Portland.
Dodds, the department's officer of the year in 2010, was shot multiple times shortly after he stopped the Dodge truck for speeding Sunday night in Lincoln City, about 14 miles north of Waldport.
Lincoln City police Lt. Jerry Palmer said Dodds was able to call in his own officer down report. The scene was captured on a patrol car video camera, but no details were being released.
The manhunt began after the gunman drove south on U.S. 101 and was spotted and chased by Newport police, with several shots fired at officers. None were hit.
The Dodge was stopped by spike strips on the highway at Waldport, where the driver fled on foot into a wooded area. The gunman also shot at a crab fisherman on a boat in Alsea Bay, near the bridge, Newport Police Chief Mark Miranda said.
The fisherman was struck by shrapnel but not seriously injured.
About 30 officers took part in the manhunt overnight. Police alerted residents through a reverse 911 system and advised them to report anyone suspicious but did not order an evacuation.
U.S. 101 was reopened shortly after 8 a.m. Monday but access to streets around the bridge was restricted, with electronic signs advising motorists about the search.
Soul Vacation Resort, located near the bridge, hired extra security guards and put employees and construction workers doing renovations on alert, said Guru Murumi, who oversees wellness programs at the yoga resort. They also checked empty rooms and notified guests.
Palmer called Dodds an outstanding officer who was well-trained and experienced.
"Steve is one of those guys you wish you could clone," Palmer said at the hospital.
Officer Tracy Burt of the Portland Police Bureau, a childhood friend of Dodds, said Dodds had grown up on the Oregon coast and lived with Burt's family during high school.
"He's like a brother," Burt said, saying the shooting left him "with just a burning pit in my stomach."