Seattle police believe the man responsible for Saturday's Capitol Hill massacre is Kyle Huff, 28, who had lived in North Seattle since moving from Montana with his twin brother about four years ago.

The assistant manager at the Town and Country Apartments where the brothers lived said police told him that Huff was the suspected shooter.

Jeff Green, a dispatcher for the Whitefish, Mont., police also said that Seattle police contacted the department Saturday and told them Huff was the perpetrator of Seattle's worst mass murder in 23 years. Huff previously lived in Whitefish.

Six people were killed in the early-morning rampage before the shooter killed himself as police confronted him. Police have not yet identified the names of the six victims. Relatives confirmed that three of those killed were Jason Travers, 32, who worked at the Madison Market food cooperative; Jeremy Martin, 26, a musician and wine salesman; and Christopher Williamson, 21, a budding disc jockey.

About 30 people were in the house at the time of the shooting. Many of them had attended a "zombie rave" Friday night at the Capitol Arts Center. The shooter, police said, left the house party around 7 a.m. He returned moments later, draped with an ammunition belt and armed with a semiautomatic handgun and a pistol-grip 12-gauge shotgun. Five people died in the home and one victim died at Harborview Medical Center.

Two other people were admitted to Harborview. The condition of one has been upgraded from critical to serious. The second person remains in serious condition.

Seattle police Chief Gil Kerlikowske would not confirm the shooter's name, saying the man's identity "has to come from the medical examiner."

According to a county medical investigator, autopsies are scheduled for Monday. "Nobody's been positively identified yet," he said of the shooting victims.

Police say they are still working to develop a motive for the slayings. Kerlikowske yesterday described the man as "quiet and humble" and said he had little previous involvement with Seattle police.

Police raided the apartment Huff shared with his twin Saturday evening. They arrived at the Town & Country Apartments in the 12300 block of Roosevelt Way Northeast with a battering ram and a shield, but they were apparently let in to the apartment by the suspected killer's brother, said Jim Pickett, assistant manager of the apartment.

Police brought out three rifles and what appeared to be a grenade, Pickett said.

Police served a search warrant on the property in relation to the shooting, said police department spokesman Sean Whitcomb. He would not give any details. He said that a man was brought in for questioning but would not identify the person.

"We did interview one person. And I cannot provide additional details on any evidence seized. But no one was arrested," he said. Pickett says the brother was taken away by police last night.

During a news conference this afternoon at Seattle police headquarters, Whitcomb said police recovered a semi-automatic rifle, a machete and hundreds of rounds of ammunition from a Dodge Laramie pickup belonging to the suspect which was found near the Capitol Hill house where the shooting occurred.

Without naming the man questioned by police, Whitcomb said police questioned someone who was later released.

Whitcomb said police still don't have a motive for the shooting and indicated they may never know one.

"They were very respectful," Pickett said about the brothers. "They practiced their drums and did it at a decent hour." He described them as "big and beefy."

A 2004 traffic citation listed Huff as 6 foot 5 and 280 pounds.

Kyle Huff, the suspected killer, was "the more purposed, the more focused. If he didn't like something he'd tell you." Huff attended the Art Institute of Seattle and then North Seattle Community College, Pickett said.

The brothers had been working as pizza deliverymen, Pickett said.

Most recently it appears Huff worked at a Pizza Hut nearby the apartment. The shift manager at the restaurant, John Edwards, confirmed Huff had worked there, but not for at least the past two months. No one could be reached at the Pizza Hut corporate office.

A couple years ago Huff worked part of a day at a nearby Domino's Pizza, said owner Art Mannikko. He said Huff walked out with no explanation part way through his first shift, hopping into a Camaro and driving off.

Pickett said the Huff brothers had never been a problem for him.

"They were very friendly, very friendly, very polite. They said 'yes sir, no sir' and they were always glad to help."

The Whitefish department provided Seattle police with information about an incident in which Huff vandalized a local art fundraiser with a shotgun in November 2000, Green said.

Flathead County, Mont., Sheriff Jim Dupont said today that Huff was booked into the jail in Kalispell after an incident in which he used a shotgun to "blow up" a sculpture of a moose that was part of a local art center fundraiser called "Moose on the Loose."

Huff, the sheriff said, was booked on felony criminal-mischief charges and was released the same day. The jail records, he said, do not disclose how the case was resolved.

"At the time, it was considered more of a prank," said Green.

Pickett said the Huff brothers had never been a problem for him.

David Postman can be contacted at dpostman@seattletimes.com; Jennifer Sullivan: jensullivan@seattletimes.com; Mike Carter: mcarter@seattletimes.com