The man, who was later found dead clutching a .38 caliber handgun and a bullet in his head, was identified as 45-year- old African-American Radcliffe F Haughton whose wife worked at the spa in a Milwaukee suburb shopping centre.
All three of those killed were women, Brookfield Police Chief Dan Tushaus said. The area near the spa in Brookfield was locked down after the incident yesterday.
The victims' ages and identities were not immediately provided. It was also not clear whether Haughton's wife was among those killed.
The incident was the second mass shooting in Wisconsin within three months. In August, six people were killed after a white supremacist opened fire at a Sikh Gurudwara.
Tushaus said the first officers on the scene found the building full of smoke from a fire believed to have been set by Haughton, who had been accused of slashing his wife's tyres two weeks before the shooting. A restraining order was placed against him and he was directed to surrender his firearms over a suspected domestic abuse case involving his wife.
President Barack Obama, who was informed about the incident, was told by his top national security officials that it was not an act of terrorism, White House Press Secretary Jay Carney said.
"The President was told there was an active shooter in Brookfield, Wisconsin. He was informed that the shooting did not appear to be terrorism-related," he said in a statement.
Obama was also briefed by FBI Director Bob Mueller, his Chief of Staff Jack Lew and Advisor for Homeland Security John Brennan. The FBI is at the site and is supporting the Brookfield, Wisconsin police department while they respond to the ongoing situation, Carney said.
President Obama has instructed the FBI to ensure that the state and local officials have full support of the Federal government, Carney added.
Brookfield police Chief Tushaus said they believe the suspect had placed an improvised explosive device inside the building where the shooting took place.
The dead man had "what appeared to be a gunshot wound to the head," wore body armor and carried additional ammunition in his pockets, a police statement said.
The injured were taken to the same hospital in Milwaukee where the injured of the Gurdwara shooting were treated.
The last of the injured of the August Gurdwara shooting was released from the hospital last week.
Meanwhile expressing shock over the incident, Wisconsin Governor Scott Walker said the state administration will provide all kind of support to the victims and their families.
"Senseless acts of violence leave us with heavy hearts and many questions. Our state will stand with the victims and their families, and we will provide them with the law enforcement and community support they need to heal in the coming days," Walker said.
Republican vice presidential candidate Paul Ryan, who comes from Wisconsin, expressed shock over the incident.
"As our community continues to heal from August's tragic violence, our thoughts and prayers are with today's victims and their loved ones. Our gratitude also goes to the first responders who rushed to save lives and secure the scene," he said.
"We will not allow the evil responsible for this heartbreaking event to triumph over the spirit of the people of Wisconsin. I ask all Americans to keep those affected by this event in their hearts, minds, and prayers today," Ryan said.
Washington/Houston: An armed man wearing body armour burst into a beauty spa where his estranged wife worked in the US state of Wisconsin and opened indiscriminate fire, killing three women on spot and wounding four others.
First Published: Monday, October 22, 2012, 09:33