A gunman with a grudge against civic leaders stormed a city council meeting early today, killing two police officers and three others before being shot dead.
The mayor was wounded in the rampage in Kirkwood, a suburb of St Louis, it was reported.
The victims at the meeting were killed after the gunman rushed the council chambers and began firing as he yelled: "Shoot the mayor," said St Louis County Police spokeswoman Tracy Panus. Two people were wounded before police shot him, she said.
The shooter killed one officer outside City Hall, then walked into the chambers and shot another before continuing to fire, Ms Panus said.
Janet McNichols, a reporter covering the meeting for the St Louis Post-Dispatch, told the newspaper that the 7pm local time meeting with about 30 people had just started when the gunman rushed in and opened fire with at least one weapon.
He started yelling about shooting the mayor while walking around and firing, hitting police officer Tom Ballman in the head, she said.
Mayor Mike Swoboda was wounded, Ms McNichols said. Public works director Kenneth Yost was shot in the head, and council members Michael Lynch and Connie Karr were also hit, she said.
The gunman also fired at city attorney John Hessel, who tried to fight off the attacker by throwing chairs, Ms McNichols told the newspaper. He then moved behind the desk where the council sits and fired more shots at council members, she said.
"Tonight our fellow Missourians in the city of Kirkwood were terrorised by a senseless and horrific crime at an open government meeting," Missouri governor Matt Blunt said in a statement.
"I join Missourians tonight in praying for the victims, their families and friends, and everyone in the community of Kirkwood."
Police have not named the victims or the shooter, but Ms McNichols identified the gunman as Charles "Cookie" Thornton, a man she knows from covering the council.
Thornton had previously disrupted meetings, she told the Post-Dispatch.
He was well-known at City Hall, often making outrageous comments at public meetings, according to a 2006 article in the weekly Webster-Kirkwood Times.
The newspaper quoted Mr Swoboda as saying in June 2006 that Thornton's contentious remarks over the years created "one of the most embarrassing situations that I have experienced in my many years of public service".
Mr Swoboda's comments came during a council meeting attended by Thornton two weeks after the man was forcibly removed from the chambers. The mayor said at the time that the council considered banning Thornton from future meetings but decided against it.
"The city council has decided that they will not lower themselves to Mr Thornton's level," Mr Swoboda said at the meeting.
Thornton said during the meeting that he had been issued more than 150 tickets.
Kirkwood is about 20 miles south west of central St Louis. City Hall is in a quiet area filled with condominiums, eateries and shops, not far from a dance studio and train station.
Mary Linehares, a teacher who lives about four roads from City Hall, described the town as quiet and eclectic.
"It's like a small town in St Louis," she said.
But despite its reputation locally for serenity, Kirkwood has grappled in recent years with crimes that have brought it unwanted attention.
Just down the street from City Hall is the Imo's pizzeria once managed by Michael Devlin, the man who kidnapped Shawn Hornbeck when the boy was just 11 in 2002 and held him for four years before authorities rescued him from the home in January last year. Also rescued was Ben Ownby, another teenager Devlin abducted just days before Devlin's arrest.
Devlin received life terms on state charges, as well as 170 years behind bars on federal charges that he made pornography.
City Hall is near a park now named after former Kirkwood police sergeant William McEntee, 43, a father of three, who was murdered in 2005 by a man who witnesses said blamed police for the death of his 12-year-old half-brother two hours earlier.
Ms Panus said the names of the victims would not be released until a press conference later today.
But Mr Swoboda, was in a critical condition in the intensive-care unit of St John's Mercy Hospital in Creve Coeur, hospital spokesman Bill McShane said.
Mr McShane said another victim, Suburban Journals newspaper reporter Todd Smith, was in a satisfactory condition.
It emerged that Thornton was arrested twice and later convicted for disorderly conduct for outbursts at two council meetings in 2006, convinced the city was persecuting him.
When allowed to speak during one meeting, he approached the podium with a posterboard with a picture of a donkey and began making harassing remarks about Mr Swoboda.
In a lawsuit stemming from those meetings, Thornton, representing himself, insisted that Kirkwood officials violated his constitutional rights to free speech by barring him from speaking at the meetings.
But a judge in St Louis threw out the case on 28 January, ruling that "any restrictions on Thornton's speech were reasonable, viewpoint neutral, and served important governmental interests".