Updated at 10:30 p.m.
A University of Arizona professor was shot and killed in an office in the Harshbarger Building on the UA campus shortly after 2:00 p.m. Wednesday afternoon.
UA police officials said they received a call just before two that a former student who should not have been in the building was on the premises.
"The moment we took the initial call in our dispatch center to the time we got officers on scene; it was just minutes. But in that short period of time that shooting was able to happen," said UA Police Chief Paula Balafas.
Late Wednesday night, University of Arizona President Dr. Robert Robbins sent an email to the university community and confirmed the victim was Dr. Thomas Meixner, the head of the Department of Hydrology and Atmospheric Sciences.
Police would not say anything about the weapon used other than to confirm it was a handgun. They also did not say how many shots were fired.
The suspect, 46-year-old Murad Dervish, was arrested during a traffic stop by DPS officers in Gila Bend a few hours after the shooting.
Officials also would not say if he had a previous professional or personal relationship with the suspect.
Classes were canceled across the university on Wednesday afternoon and all non-essential employees and students were asked to leave campus.
Professor Roberto Guzman, who teaches environmental and chemical engineering, told AZPM just after the shooting that he was in the building at the time and heard multiple gunshots.
"Then when we went outside to check for my students, there were empty shells outside of the hydrology building office," Guzman said.
At a news conference Wednesday, Balafas urged students and faculty to seek mental health resources following the shooting.
The university set up a web page with information about the shooting and the investigation.
Christopher Conover contributed to this report.
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