Professor Thomas Meixner Of Arizona University Allegedly Shot Dead on Campus by Ex-Student

“It’s a tremendously tragic event. We feel so incredibly bad for the professor’s family, friends, and colleagues, and our hearts really just go out to them,” University Police Chief Paula Balafas said during a press conference shortly afterward.

A staff member informed the UAPD of the presence of a former student who had entered the facility without authorization just before the shooting, according to Balafas.

Sadly, the UAPD’s officers were unable to arrive at the John W. Harshbarger Building in time to stop the shooting, during which a handgun was determined to have been used. The staff member had asked that police accompany the ex-student of the property.

After the shooting, the gunman reportedly ran from the building. Officers from the Arizona Department of Public Safety later apprehended former University of Arizona student Murad Dervish, 46, at a traffic stop outside the town of Gila Bend at 5:10 p.m, some 120 miles from the murder scene.

Dervish was booked in the Pima County Jail at 6:20 p.m., Sgt. Sean Shields of the UAPD told PEOPLE. He was charged with murder in the first degree, pre-meditated, and aggravated assault with a deadly weapon.

Balafas shared that the UAPD currently does not know of a motive for the shooting.

The University of Arizona canceled all its classes following the tragic event and instructed students to either go home or return to their dorm rooms. Counseling services were also made available to students, per the school.

“Arizona is praying for the family and friends of the professor and those affected by today’s tragedy in Tucson,” Arizona Gov. Doug Ducey wrote on Twitter.

In an image shared on the UAPD’s Instagram page, flowers can be seen sitting outside of the Harshbarger Building sign in honor of the victim, as the sign is surrounded by caution tape.

“I am in complete shock,” wrote coworker Dr. Laura Meredith. “We just submitted a grant last week. I can’t think of a nicer or more supportive colleague/mentor/human. This is devastating and senseless. How sorry I am for so many people now in pain.”