SEATTLE -- Numerous law enforcement agencies are working to find whoever fatally shot a Seattle police officer in "an assassination" of the officer on Halloween night, said Assistant Police Chief Jim Pugel.

Police, speaking at a news conference Sunday afternoon, identified the slain officer as Timothy Brenton, 39.

Pugel said the shooting happened in the Leschi neighborhood, near the intersection of 29th Avenue and East Yesler Way, just after 10 p.m. Saturday.

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Pugel said Brenton was training a female student officer, Britt Sweeney, 33, in a marked patrol car. The two were discussing a routine traffic stop when a car pulled up next to their parked car, and someone fired multiple shots.

Brenton, who was in the patrol car's passenger seat, was struck multiple times and killed instantly. Sweeney ducked, and a bullet grazed her back. She got out of the patrol car and returned fire several times as the shooter's vehicle fled.

"This is an assassination," Pugel said.

"It was an attack on each and every member of the Seattle community," said Seattle Mayor Greg Nickels, who noted that it was the first intentional homicide of a Seattle officer since 1994.

"We will not rest until the assailant is brought to justice," Nickels said.

"Every single police department (resource), police employee, as well as numerous local and federal agencies are looking at this," said Pugel. "Every resource is being used to bring it to a conclusion."

Anyone with information can call the Seattle Police Department Tip Line at 206-233-5000, call Crimestoppers at 206-343-2020 or send a text message to Crimestoppers by texting tip486, then send to 274637.