PHOENIX (AP) — The most seriously wounded of three people shot in a community college computer lab had punched the gunman, an old enemy, in the face before he opened fire, police said Friday.

Isaac Deshay Smith was sentenced to jail for attacking Rodney Smith in December, and the two unrelated men had gotten into verbal confrontations every time they met since then, Phoenix detective Reuben Gonzales said.

On Thursday, police said, Isaac Smith, 19, punched 22-year-old Rodney Smith during a confrontation at South Mountain Community College.

Rodney Smith, like Isaac Smith a former student of the school, then pulled a handgun from his waist and opened fire, according to a probable cause statement released Friday. School officials say 20 to 30 people were in the lab, which is open to the public.

Isaac Smith underwent emergency surgery overnight and was in critical condition Friday at Maricopa Medical Center.