Update: Edmonton police are searching for Travis Brandon Baumgartner, another G4S employee who is a person of interest in the shooting. The police released his name and photo at a press conference on Friday.

EDMONTON - The search was on for suspects Friday after a midnight heist at an ATM machine on the University of Alberta campus left three armoured guards dead and one in critical condition.

Police were releasing few details, but one bystander photo posted to Facebook showed three people from G4S lying in front of a TD bank machine, emergency crews working over the bodies. There were blood streaks on the concrete floor out from behind the machine to where the bodies were lying.

"It's devastating," said G4S spokeswoman Robin Steinberg, who confirmed the deaths and injuries. Names were not released.

"Our hearts go out to families of the victims and all of our employees at the Edmonton branch. I've been working for this organization for 5 1/2 years and to see something like this is beyond tragic. It just hits you to the core."

Steinberg confirmed the guards were armed, but would say little else about what is believed to have happened.

"I have no details," she said.

TWITTER REACTION

"It is under police investigation and we are doing everything we can obviously to co-operate with the police and hopefully they can apprehend this person, or people. I am not even sure how many are involved."

The robbery occurred around 12:30 a.m. at HUB Mall, a long, thin rectangular block of shops, eateries and student apartments on the east end of campus, which sits on the south side of the North Saskatchewan River and across from Edmonton's downtown skyscrapers.

The mall is built up over an access road. The third fatality was found on the road, underneath the super-structure and below the shooting scene.

Student residents, who live in apartments above the stores, reported hearing shots.

Ravedh Seeberath told CBC News he was studying when he thought heard the sound of fireworks.

"I heard pop, pop, pop, about eight of them," Seeberath told Global Edmonton. "I saw about 30 tactical guys rushing towards me with a dog."

Police and tactical units swarmed the campus and found the bodies by the machine at the north end of the mall, which links up to a number of surrounding buildings by covered passageways.

Ian Breitzke said he saw police pulling out bodies. The 21-year-old accounting student said he was watching TV in his residence room and heard a man in a room behind an ATM crying out in pain.

"When the police came in about 10 minutes, they ended up busting down the door (of the ATM room) and pulling out all the bodies that were in there," he said.

"Another couple of moments after that (they) pulled the man who was still alive out of the room."

About 560 students are living in residence at the mall at this time of year.

The scene had a puzzling twist. While one G4S vehicle was located at the scene, a G4S armoured truck was found some distance away in an east Edmonton industrial park near the G4S offices.

The truck had been left idling, parked at an angle at the side of the road. Police had the area around the truck blocked off Friday and were investigating.

G4S is an international security company with more than 630,000 employees. It has a specialized cash-management arm that delivers pay packets to fill ATMs.

Police didn't discuss how, or if, the second vehicle was tied to the university robbery and would only say the shooting was an "attempted armed robbery."

A police news conference was planned for later Friday morning.

The university was put in lockdown after the shooting. Any students leaving their rooms in the residence were being told they could not return until 7 p.m.

The university confirmed that it did not send out an emergency alert to students on its internal website system when the shooting happened. Instead, police went door to door in the residence telling people to stay inside.

Police spokesman Scott Pattison did confirm no students were involved in the shooting.

The school offered a statement about the shooting on its website.

"The university is saddened about those who lost their lives last night and we extend our condolences to their loved ones," the statement said.

"The safety and security of our students and staff is our first priority and our campus protective services are working closely with Edmonton police."

Grief counsellors were made available for students living at the HUB residence, and students too traumatized to write exams were being allowed to defer them.

The rest of the university was operating as normal and scheduled exams were going ahead.

It was the second robbery of a G4S armoured vehicle in Edmonton in recent months. Last December, guards making a mid-afternoon pickup outside a casino were attacked and pepper-sprayed by two masked men. The pair fled in a Jeep with an undisclosed amount of money.

With files from the Huffington Post Canada

Also on HuffPost