KNXV-TV: Arthur D. Harmon had legal battle with man he allegedly shot PHOENIX, Jan. 31 (UPI) -- Phoenix police sought an armed 70-year-old man suspected in an office shooting that left a legal adversary dead and the dead man's lawyer critically wounded. The suspect, Arthur D. Harmon, was reported in a legal battle with a telephone call center, KNXV-TV, Phoenix, reported. The call center's chief executive officer, Steven D. Singer, 48, was killed in the shooting. A lawyer representing Singer was shot and in critical condition. Officers early Thursday hunted Harmon, last seen in a white 2013 rented four-door Kia Optima with Arizona license plate AVS-2052, Sgt. Tommy Thompson said. Police consider Harmon armed and dangerous, Thompson said. Police said Harmon shot at someone trying to follow him to get his license plate number after the 10:30 a.m. Wednesday shooting. Authorities said Singer, head of Fusion Contract Centers Inc., was attending a mediation session at a law firm at the office building, The Arizona Republic reported. Attorney Mark Hummels, 43, who KNXV-TV said represented Singer, was shot in the neck and lower back and was in critical condition, Larry Hammond, a partner with the Osborn Maledon law firm, where Hummels worked, told the Republic. Hummels, like Singer, was shot after leaving a mediation session, another lawyer told the newspaper in an email. Bystander Nichole Hampton, 32, was shot in the hand. Hampton is the human resources director of a home health services company located in the complex. Three other people were taken to the hospital with unspecified injuries, the Republic said. Multiple schools were locked down immediately after the shooting. It was unclear if they would reopen Thursday.