Police are searching for a 70-year-old man suspected in an Arizona office shooting that left one dead and two wounded, saying that he is "armed and dangerous".
Police identified the suspect as Arthur D Harmon.
They identified the man who died hours after the Wednesday morning shooting as 48-year-old Steve Singer. He is the CEO of Fusion Contract Centers.
Police say a 43-year-old man was listed in critical condition along with a 32-year-old woman. Police did not release the names of the wounded, but a Phoenix law firm said one of their lawyers was among them. It said Mark Hummels was representing a client in mediation.
The gunfire at the office complex prompted workers to lock the doors to their offices and hide far from the windows.
As police searched for the gunman, SWAT teams and two armoured vehicles surrounded his house about seven miles from the shooting scene in Phoenix. Police served a search warrant to enter the home. For a time, officers, believing the man was inside, used a megaphone to tell him to surrender.
America's latest public shooting came on the same day the US Congress took up the issue of gun control for the first time since the Connecticut school shooting in December left 20 young children dead and changed the national conversation on guns. Former Arizona congresswoman Gabrielle Giffords, who was shot in the head during a 2011 gun rampage in Tucson that left six people dead, appeared in Washington to urge stricter gun controls.
The gunman arrived at the office building at about 10.30am and got into a dispute with someone, a conflict that escalated to the point where he drew a gun and shot three people, Sgt Tommy Thompson said.
"Everyone was just scared, honestly, just scared," said Navika Sood, assistant director of nursing at First at Home Health Services who, along with her co-workers, locked the entrances to their office.
Ms Sood said police evacuated the office about 30 minutes after she first heard the popping noises.