"I was born here, I was raised here! This is my ultimate dream!" shouted John Caro, who, with his wife Corina, both 59, whooped their way down Lake City Way in North Seattle and high-fived passersby. "We have waited so freakin' long for this!"
The Seahawks beat the Denver Broncos 43-8 Sunday. The last time a major Seattle sports franchise won a championship was in 1979 when the Supersonics took the NBA title. The WNBA's Seattle Storm have won two championships, in 2004 and 2010.
Seattle police were out in large numbers in many neighbourhoods after the game. The department was investigating two shootings that came amid widespread celebrations over the Seahawks' Super Bowl win, both near the Pioneer Square neighbourhood, where thousands of fans gathered.
The separate incidents occurred just before 12 a.m. Monday and left two victims hospitalized with non-life-tfhreatening wounds, police spokesman Mark Jamieson said. The suspect in the first shooting was apprehended when officers in the area heard the shots and saw him running. No one has been arrested in the other shooting.
The motives for the shootings remained unclear.
For most of Sunday night the crowd was in a celebratory mood, but later on it turned ugly, with people hurling bottles at police and breaking windows, Jamieson said. Officers in riot gear eventually dispersed the crowd.
The Fire Department reported about a half-dozen bonfires around the city, mostly involving couches and mattresses burned in streets. The biggest blaze was near the University of Washington, where one person was arrested for investigation of reckless burning.
In all, about six people were arrested, including the suspects in the burning and shooting cases, Jamieson said.
In Occidental Park in Pioneer Square, near CenturyLink Field where the Seahawks play, people waving "12th Man" flags took to the streets, and others climbed trees and sculptures.
They broke 17 glass panes and caused other damage to a historic pergola that will cost about $25,000 to repair, Joelle Hammerstad, a Parks Department spokeswoman, said Monday.
People in some neighbourhoods blocked traffic, and in downtown a line of cars stretched for blocks as people cheered.
Seattle police spokesman Mark Jamieson said Sunday night the biggest concentrations of people were downtown and in the University District. He said no major disturbances were reported.
By contrast, the mood in Denver was subdued, as expected, with fans downcast and police reporting few problems.
Mayor Ed Murray said in a statement that a Seahawks victory parade would occur Wednesday, with a route through downtown and ending at CenturyLink Field.
Shrieking and waving her Seahawks flags at passing cars on a North Seattle street, Senayet Woldemarian, a 29-year-old physical therapist from suburban Shoreline, said: "We got our first Super Bowl!"
Her friend, wedding photographer Taylor Olcott, 28, said it reminded her a little of being in Boston in 2004, when the Red Sox won baseball's World Series for the first time since 1918.
"This is the first time I've really seen Seattle passionate about anything," she said. "It's, like, East Coast. It's very exciting."
About 30 people watched the game at the Outlander Brewery in Seattle's Fremont neighbourhood. It was such a blowout that by the fourth quarter, employees had switched one of the three TVs to Animal Planet's "Puppy Bowl."
"We're all in euphoria right now," said Steve McVay, a 43-year-old Seattle IT worker. "It's a huge deal for the city. Since the Sonics, we haven't won anything."