Updated at 9:42 a.m. EST.
A suspect in the slaying of four police officers who werein a suburban coffee shop was surrounded by police at a Seattle house early Monday, wounded and possibly dead, police said.
Negotiators were trying to communicate with Maurice Clemmons, 37, using loudspeakers, explosions and even a robot to try to prod him from hiding. At one point, gunshots rang through the neighborhood, about 30 miles from the original crime scene.
"We have determined that in fact he has been shot," said Ed Troyer, a spokesman for the Pierce County Sheriff. "He may be deceased from his gunshot wound."
During an appearance on CBS' "The Early Show" Troyer said that Clemmons' wound was possible "severe."
Clemmons, who has a long criminal history - including a long prison sentence commuted by former Arkansas Gov. Mike Huckabee nearly a decade ago - became the prime target Sunday in the search for the killer of Lakewood police Sgt. Mark Renninger, 39, and Officers Ronald Owens, 37, Tina Griswold, 40, and Greg Richards, 42.
Authorities had speculated early Sunday that the gunman might have been wounded at the coffee shop by one of his victims. Troyer said interviews with others detained in the investigation confirmed that theory.
Police surrounded the house late Sunday, and a negotiator used a loudspeaker early Monday to call him out by name, saying: "Mr. Clemmons, I'd like to get you out of there safely. I can tell you this, we are not going away."
Any response from inside the house was inaudible from the vantage of a photographer for The Associated Press. But shortly thereafter, police began using sirens outside the house, and there were several loud bangs before the negotiator resumed speaking, saying: "This is one of the toughest decisions you'll make in your life, but you need to man up."
By 3 a.m. Pacific time, the loudspeakers and explosions had fallen silent. Seattle Police spokesman Jeff Kappel said Clemmons has never responded.
The shootings are the deadliest attack ever on police in Washington, reports CBS News correspondent John Blackstone.
Clemmons is believed to have been in the area of the coffee shop around the time of the shooting, but Troyer declined to say what evidence might link him to the shooting.
Investigators say they know of no reason that Clemmons or anyone else might have had to open fire on the four officers as they sat working on their laptops early Sunday morning, catching up on paperwork at the beginning of their shifts.
"We're going to be surprised if there is a motive worth mentioning," said Troyer, who sketched out a scene of controlled and deliberate carnage that spared the employees and other customers at the coffee shop in suburban Parkland, south of Seattle.
Troyer said teams of investigators were working on various aspects of the case, including tracing Clemmons' finances, looking into his past arrests and other criminal history and canvassing neighbourhoods he was known to frequent.
"We've been on his trail and we're still on his trail," Troyer said.
Richards' sister-in-law, Melanie Burwell, called the shooting "senseless."
"He didn't have a mean bone in his body," she said. "If there were more people in the world like Greg, things like this wouldn't happen.
Clemmons has an extensive violent criminal history from Arkansas, including aggravated robbery and theft, the sheriff's office said. He also recently was arrested and charged in Washington state for assaulting a police officer, and second-degree rape of a child. Using a bail bondsman, he posted $150,000 - only $15,000 of his own money - and was released from jail last week.
Documents related to the pending charges in Washington state indicate an unstable and volatile personality. In one instance, he is accused of punching a sheriff's deputy in the face, The Seattle Times reported. In another, he is accused of gathering his wife and young relatives and forcing them to undress, according to a Pierce County sheriff's report.
"The whole time Clemmons kept saying things like trust him, the world is going to end soon, and that he was Jesus," the report said.
The four officers were with the 100-member police department of Lakewood, which adjoins the unincorporated area of Parkland.
An impromptu memorial of an American flag, flowers and candles decorated the front yard at Renninger's home on Sunday night. A motorcade of dozens of police cars and motorcycles with lights flashing escorted the bodies of the four officers to the medical examiner's office.
Troyer said investigators believe two of the officers were killed while sitting in the shop, and a third was shot dead after standing up. The fourth apparently "gave up a good fight."
"We believe there was a struggle, a commotion, a fight ... that he fought the guy all the way out the door," Troyer said. "We hope that he hit him." Investigators were asking area medical providers to report any gunshot wounds, although it wasn't clear that the gunman was wounded.
An electronic tracking bracelet police believe Clemmons was wearing at the insistence of the bail-bond company was found cut off by police on Sunday, Troyer said. Clemmons is believed to have associates who have helped him evade police in the past, Troyer said.
In 1989, Clemmons, then 17, was convicted in Little Rock for aggravated robbery. He was paroled in 2000 after Huckabee commuted a 95-year prison sentence. Huckabee, who was criticized during his run for the Republican presidential nomination in 2008 for granting many clemencies and commutations, cited Clemmons' youth. Clemmons later violated his parole, was returned to prison and released in 2004.