(CNN) -- Canadian authorities were preparing Friday to file warrants for murder against a 21-year-old security firm employee in the robbery of an armored vehicle at the University of Alberta that left three other security employees dead and a fourth critically injured, police said.
Edmonton police were in the process of filing Canada-wide warrants for three counts of first-degree murder and one count of attempted murder against Travis Brandon Baumgartner of Edmonton, said Bob Hassel, superintendent of the Edmonton Police criminal investigations division.
"With the approval of the Crown, we now believe we have reasonable, probable grounds, that this is the person responsible for this terrible crime," Hassel told CNN.
Police said they believe Baumgartner is "armed and dangerous" and are urging the public to use extreme caution should anyone happen to encounter him.
Baumgartner is an employee of the security firm G4S, company spokeswoman Fiona Walters told CNN. The firm, which specializes in outsourcing, has more than 657,000 employees and operates in 125 countries, its website says.
The three people killed and the one person critically injured are also G4S employees, Walters said.
"We are shocked and horrified by the incident and would like to express our heartfelt condolences to the victims' families and to all of our employees in Edmonton," the firm said in a statement. "We are doing everything we can to assist the Edmonton Police with their investigation."
Earlier in the day, Canadian authorities said they were searching for Baumgartner as a "person of interest" in the shooting at the university in Edmonton early Friday.
An emergency notice by the university said the shooting happened during an armored car robbery.
Investigators were trying to find Baumgartner because he "is believed to be one of several armoured company employees that attended the U of A around midnight" on Friday "to make a delivery," Edmonton police said in a written statement.
Authorities also released a photograph of Baumgartner.
Investigators "confirmed the shootings were the result of an armed robbery of an armoured vehicle making deliveries at the U of A's Hub Mall building," police said in their statement.
Officers were called to the campus and found three bodies and a fourth victim with life-threatening injuries, police said.
The area where the shootings occurred remained closed off, but the university said exams and other university business will proceed as scheduled.
Police did not immediately release the names of the victims, pending notification of next of kin.
CNN's Jake Carpenter contributed to this report.