A gunman opened fire Saturday morning in a rental home occupied by about 20 young partygoers, killing four young men and two women and critically injuring at least one other person before committing suicide when confronted by police on the steps outside.

William Lowe, 59, who lives across the street, said he heard six shots fired shortly after his alarm went off at 7 a.m. He looked through the peephole of his door to see people scattering from the home.

Some of the guests had their faces painted and hair dyed for a "zombie party" held Friday night, Police Chief Gil Kerlikowske said.

One man staggered out and sat down, Lowe said, and a large man dressed in black — about 6-foot-1 and maybe 225 pounds — came out carrying a shotgun across his chest. When an officer standing in the street told him to put the weapon down, he put the barrel in his mouth and fired.

Officers found three dead in the living room, one at the front door and another on the porch steps. Three people were taken to Harborview Medical Center; one died, one was in extremely critical condition and the third was stable, the nursing supervisor said. Officers transported about a dozen witnesses to a precinct to interview them.

The victims were in their late teens and early 20s, police said. Officers said they were not yet aware of a possible motive.

"It's one of the largest crime scenes the city has ever had," Kerlikowske said.

Dozens of rounds were fired in the house, where people — ranging from their early and mid teens to mid-20s — gathered after a larger party called "Better Off Undead" in the Capitol Hill neighborhood. Some of the guests were "made up to look as if they were dead," the chief said.

He said the shooter, who had been invited to the party at the home, left the house about 7 a.m. and came back 10 minutes later heavily armed.

As the gunman walked the half block from his black Dodge pickup truck, he apparently spraypainted the word "NOW" in orange twice on the sidewalk and once on the steps of a neighbor's home, police said.

When he got to the house, he immediately opened fire before forcing his way inside. He shot two people outside, three in the living room and then went upstairs looking for more victims, Kerlikowske said.

Just before the shooting started, a 20-year-old Bellevue man told The Seattle Times, his 17-year-old girlfriend called him to an upstairs bathroom to talk while she applied makeup. Most everyone else in the house had been asleep about five hours, said the man, who was not identified.

"We heard gunshots and screaming and I opened the bathroom door and looked down the stairs and saw flashes from the gunshots. It was pretty intense," he said.

He locked the door and he and his girlfriend crouched in the bathtub.

"After all the gunshots, the shooter came upstairs and tried to open the door. He shot a round through the door and the bullet whizzed by my face," the man said.

The gunman then went back downstairs, he said.

"We thought we were going to die, plain and simple," said the young man, interviewed outside the downtown police station where he said he was among a group of about 30 partygoers questioned by police.

Kerlikowske said an officer in the neighborhood heard the shots and arrived to find one person staggering out of the house with a gunshot wound. The officer confronted the man with a shotgun but got no further than "Drop your ..." before the man turned the weapon on himself, the chief said.

The gunman also had a handgun, police said. Kerlikowske said the gunman mainly used the 12-gauge pistol-grip shotgun, "a weapon not designed for hunting purposes but for hunting people."

The gunman was wearing bandoliers of shells for the shotgun and carrying additional clips for the handgun. In his truck, police found an assault rife and multiple "banana clips" carrying 30 bullets each.

Police said they did not know if drugs or alcohol were a factor, though Kerlikowske said marijuana and alcohol were found in the house.

"This is a terrible tragedy for all of the victims and their families," said Mayor Greg Nickels in a statement.

"This kind of gun violence is extremely unusual for Seattle and this neighborhood," he added. "We don't know the exact reason, but we do know that it wasn't random.:"

Neighbor Cesar Clemente, 25, said he called 911 when he heard the shots. He looked outside to see people fleeing, and two people huddling in the bushes. He called for them. One, a man, made it to his front entryway, shot in the arm and the abdomen. The other collapsed in the bushes.

Clemente asked the man what happened. He said only, "I've been peppered." Medics quickly took him away, leaving behind a few shotgun pellets on the floor where he had been lying.

Lowe said people came and left the house at all hours, often with facial piercings and elaborate makeup.

"This was a destination point," he said.

Nancie Thorne told The Seattle Times that her 15-year-old daughter, Suzanne, was in the house when the man opened fire. She hadn't heard if her daughter survived.

The girl's boyfriend, Jesse Mullens, called Thorne earlier Saturday to say they had gone to the house following a "zombie rave" Friday night, Thorne said. They were about to leave — Mullens was waiting outside — when the gunman barged in.

Mullens told Thorne he heard a lot of gunshots. He thought Suzanne was stuck somewhere in the house with the shooter between her and the door.

"It's the worst phone call a mom can get," Thorne said, crying. "She shouldn't have gone to the rave. I've never approved of those things. ... I just hope to God she's alive. And if she is, she's grounded for life."

Hospital officials said the girl was not there.

Aaron Hoyle, 25, of Renton, said about five people in or near their 20s lived in the blue, two-story bungalow with white trim, and that some were promoters of warehouse parties. Hoyle hadn't been to the home in about three months, but came to see if his friends were OK when he heard about the shooting on the news.

The home, which according to King County property records is owned by a man named D. Gregg Doyle, is just a few blocks from Miller Community Center, where Little League baseball games were under way Saturday morning.