(CNN) -- A hero hurled barstools at a gunman as he opened fire inside a Seattle cafe, police said Thursday.
Police did not release the witness' full name, but said his actions allowed three people to escape while a man armed with two handguns attacked on Wednesday.
"There's a hero. .... He put his life at risk," Assistant Police Chief Jim Pugel told reporters.
In an interview with police, the man said he had glanced at his phone when he heard gunshots, then sprung into action as he saw people scrambling around him.
"I just threw the frigging stool at him, legs first," the man said in a statement published on the official Seattle police blog.
The man, who authorities said they were only identifying as Lawrence to protect his privacy, told police he made a vow after his brother died in the World Trade Center terror attacks.
"I promised myself (if something like this ever happened), I would never hide under a table," he said, according to police.
The shooting Wednesday left four people dead and one person critically injured inside Cafe Racer, a peaceful coffeehouse in the city's University District. A second shooting, about a half-hour later near downtown Seattle, left a woman dead, authorities said.
The suspect in both shootings, identified by police as Ian Stawicki, died Wednesday night, several hours after he shot himself in the head as a five-hour police manhunt came to an end.
Witnesses told police the gunman began shooting after an employee at the coffee shop asked him to leave.
Police said that a new piece of evidence investigators viewed Thursday showed the gunman opening fire in the cafe, where patrons were reading books and chatting over coffee.
"One person stands up, looks like he's going to go outside for a minute. At that point the suspect stands up and starts shooting ... and then just goes down the bar. He chases a few people," Pugel said. "At that time he's been hit by the stool, twice. He completes the shooting, puts the guns in his pockets, actually took a hat from one of the victims, put it on his head and walked out."
Police said they were shocked by the apparently senseless violence.
"In my almost 30 years in this department I've never seen anything more horrific and callous and cold," Deputy Chief Nick Metz said.
Witnesses described the shootings in several 911 recordings released by police Thursday.
"Someone came in and shot a bunch of people. I'm hiding in the bathroom. We need help right away. ... There's people down all over the place out there," one man calling from Cafe Racer said.
A female caller told dispatchers she saw a gunman assaulting a woman in a parking lot in downtown Seattle, then shooting her, stealing her black Mercedes and running her over as he sped away.
Authorities will continue their investigation into the shootings for several weeks, but are "very confident" that Stawicki is the only suspect, Pugel said.
The violence left Seattle reeling Thursday.
"Our department and the whole city is just trying to catch its breath from yesterday's events," Metz said.
Two of the victims at Cafe Racer were members of a local folk band, God's Favorite Beefcake, according to CNN affiliates. They were found dead at the coffeehouse. A woman and a man died later at a hospital. A fifth person was in critical condition, police said, but was not expected to survive.
The suspect's brother, Andrew Stawicki, told The Seattle Times that Ian Stawicki had long struggled with mental illness, but refused to talk about that or his anger.
"Someone like that is so stubborn, you can't talk to him," he told the newspaper. "It's no surprise to me this happened. We could see this coming. Nothing good is going to come with that much anger inside of you."
A Wednesday night meeting was held in the city's Central District, where Mayor Mike McGinn and police officials discussed a recent spike in violence in Seattle, KOMO reported.
"If violence is a disease, our city is infected," said Paul Patu, of the city's Youth Violence Prevention Council, according to CNN affiliate KCPQ. "When old people are afraid of young people, something is wrong. We have to commit to getting to know each other and stop being strangers."
Seattle, a city of about 600,000, recorded 20 homicides in 2011, according to Police Department statistics. Wednesday's shootings bring 2012's year-to-date total to 21, according to KOMO. Two cases have been cleared, and seven arrests were made.
Two other people have died in random shootings in Seattle in the past month, according to CNN affiliates. In late April, a 21-year-old woman died in an apparently random drive-by shooting near downtown. And a 43-year-old man died last week while driving down the street with his family. Police said the gunman's intended target in that shooting was another person involved in a dispute with the gunman. No arrests have been made in either case.
On Saturday, a bystander was wounded near the city's landmark Space Needle when he was struck by a bullet allegedly fired by a gang member involved in a dispute with another man, according to KIRO.
McGinn acknowledged at a news conference that the violence had shaken the city, KIRO reported.
"It's going to take our political leaders coming together to give our police officers the support and tools they need to do their jobs," McGinn said.