Authorities identified the suspect as 70-year-old Arthur D. Harmon. Sgt. Tommy Thompson said Harmon arrived at the office building at about 10:30 a.m. At the end of a mediation session, he drew a gun and opened fire.
The building off 16th Street north of Glendale Avenue was evacuated, and multiple police vehicles and fire trucks were seen outside the office complex.
One shooting victim died at the hospital. Police say a 43-year-old man and a 32-year-old woman remain in critical condition.
According to court documents, Harmon was scheduled to go to a law office in the same building where the shooting took place for a settlement conference in lawsuit he filed last April against Scottsdale-based Fusion Contact Centers LLC. The company had hired him to refurbish office cubicles at two call centers in California, but a contract dispute arose.
As police searched for the shooter, SWAT teams and two armored vehicles surrounded his house. Police served a search warrant to enter the home. For a time, officers believed the shooter was inside, using a megaphone to say: "We don't want to get hurt and we don't want to hurt you. Don't make it any worse than it is right now."
The Associated Press contributed to this report.