A shooting at a spa near a Brookfield, Wis., mall on Sunday left four dead--including the shooter--and four others wounded, police said. The suspected gunman, 45-year-old Radcliffe Haughton, of Brown Deer, Wis., was later found dead inside.

The shooting occurred at the Azana Spa across the street from the Brookfield Square Mall at approximately 11:15 a.m. local time, police said. Inside the spa, police found what appeared to be an improvised explosive device (IED), and a bomb squad was called in as officials worked to clear the two-story building.

"Our entire operation is focused on locating the suspect," Brookfield Police Chief Daniel Tushaus said at a press conference earlier Sunday.

A spokeswoman for Froedtert Memorial Hospital told the Associated Press that said four shooting victims were being treated for non-life threatening injuries at the hospital.

Authorities did not immediately release a motive. But according to the Milwaukee Journal Sentinel, a restraining order requested by Haughton's wife was issued against him on Thursday in Milwaukee County Circuit Court. And according to WISN-TV, she worked at the spa.

Online court records showed that Haughton "was not allowed to have firearms and was directed to deliver firearms to the sheriff," the Journal Sentinel said. "The order does not indicate if that happened."

Following the shooting, the mall and a nearby country club were placed on lockdown. SWAT, FBI, fire and rescue officials responded to the shooting, and a Flight for Life helicopter landed in the mall's parking lot. Police and tactical units conducted a sweep of surrounding businesses.

A representative from the Department of Homeland Security arrived on the scene to offer investigative assistance, while police and FBI--assisted by a bomb squad--conducted a search of Haughton's home.

Earlier, a reporter from the Journal Sentinal spoke to the suspect's father, Radcliffe Haughton Sr., who said he told his son last week, "Don't do anything stupid."

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Meanwhile, employees at the spa were asked to not speak to the media. "It is so important that things get figured out and settled first," a post on Azana Spa's Facebook page read. "Please continue to pray for all of those involved."

The suspect did not appear to have a presence on Facebook, but a Google Plus page for a Radcliffe Haughton includes a photo of a man who looks like Haughton displaying what appears to be a gun. A LinkedIn page lists Haughton as the owner of "Haughton International Corporation."

Rep. Paul Ryan, campaigning as the Republican vice presidential nominee in Iowa on Sunday, said he was "shocked and saddened" by the news out of his home state.

"As our community continues to heal from August's tragic violence, our thoughts and prayers are with today's victims and their loved ones," Ryan said in a statement. "Our gratitude also goes to the first responders who rushed to save lives and secure the scene. 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."

Sunday's shooting comes less than three months after Wade Michael Page, an Army veteran with white supremacist ties, opened fire at a Sikh temple in Oak Creek, Wis., killing six and injuring three others before shooting himself.

And the spa is less than a mile from a hotel where a gunman opened fire during a Living Church of God service in 2005. Seven people were killed and four wounded in that shooting.