MILWAUKEE - Three people were killed and at least four injured in a shooting on Sunday at a Milwaukee, Wisconsin, spa, Brookfield Police Chief Daniel Tushaus said.

The suspected gunman, who has not been caught, was identified as 45-year-old Radcliffe Haughton of Brown Deer, Wisconsin, authorities said.

"We believe we have three deceased," Tushaus said at a news conference. "The investigation is fluid and ongoing. We have a number of scenes being worked on as we speak, not only the salon but the suspect's residence in Brown Deer."

The carnage marked the second mass shooting at a U.S. beauty spa in a matter of days. On Thursday, a gunman opened fire at a beauty salon in suburban Orlando, Florida, killing three women and wounding another before fleeing and committing suicide at a nearby residence.

In Wisconsin, police said they found what appeared to be a bomb, described as an improvised explosive device, at the salon where the shooting occurred on Sunday morning. It triggered a lockdown at a nearby suburban shopping center, The Brookfield Square mall.

According to the Wisconsin court system, a temporary restraining order related to domestic abuse was issued against Haughton on Oct. 8 in Milwaukee County. On Oct. 18, an injunction was granted prohibiting Haughton from possessing a firearm.

There was also an incident of misdemeanor disorderly conduct, described as domestic abuse, issued against Haughton for an incident on Jan. 8, 2011. The charge was dismissed on June 15, 2011.

Leonard Peace, an FBI spokesman in Milwaukee, said no arrests had been made in connection with the shooting.

Members of an FBI Special Weapons and Tactical Team (SWAT) and other personnel were backing up local police as part of the follow-up to the shooting, Peace said.

Four victims with gunshot wounds were rushed to Milwaukee's Froedtert hospital, but none of their injuries were life-threatening, said Carolyn Bellin, a hospital spokeswoman.

Hours after the shooting, heavily armed SWAT teams and tactical units were combing the area and the mall was cordoned off.

Wisconsin Governor Scott Walker issued a statement calling the shooting another example of the "senseless acts of violence" that occur across the country.

"Our state will stand with the victims and their families," he said.