BROOKFIELD, Wisconsin -

A gunman is believed to have killed three people and wounded four others at a hair salon and spa near a mall in Brookfield, Wisconsin, Police Chief Daniel K. Tushaus said Sunday.

Police are searching for Radcliffe Haughton, 45, of Brown Deer, Thomas Ahern, a spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives said.

The shooting is being investigated as a possible domestic-related incident, he added.

Tushaus said Haughton is 6-foot-1 and weighs 270 pounds, and was wearing a gray sweater and blue jeans.

Employees told authorities the man entered the salon with a handgun and opened fire when asked if he was going to rob the store, Ahern said.

Haughton is still at large, the police chief said, adding that SWAT officers are still searching the salon.

Police "believe we have identified what is being described as an improvised explosive device," in the salon the chief said, adding that the device was hampering the investigation.

Beth Strohbusch of Froedtert Hospital in nearby Milwaukee told CNN that none of the four victims who had arrived there were in critical condition.

The hospital complex, which includes a medical school, is on lockdown, according to the Froedtert website.

The spa is about half a mile from a Sheraton hotel where a gunman killed seven people and himself in March 2005. Terry Ratzmann, 44, burst into a service being held by a Living Church of God congregation and fired 22 rounds before shooting himself.

Wisconsin Gov. Scott Walker released this statement on the shooting: "As we wait for further details from the shooting today in Brookfield, Tonette and I send our thoughts and prayers to the victims. 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."