Three killed, 4 injured in US shooting; suspect found dead

Three people were killed and four others injured when a suspected gunman, who was later found dead, opened fire at a spa in a Milwaukee suburb shopping centre in the US state of Wisconsin.

President Barack Obama, who was informed about Sunday's incident, was told by his top national security officials that the incident 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," Carney said in a statement.

Obama was 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, he said.

According to local police and federal investigating agencies, the suspect was identified as Radcliffe F Haughton, the 45-year-old husband of a spa worker.

Haughton, an African-American, was later found dead.

Brookfield police Chief Daniel Tushaus said they believe the suspect had placed an improvised explosive device inside the building where the shooting took place, which he said was hampering the their efforts to clear the building.