Police are searching for a person of interest after an attempted armed robbery that left three people dead and one in critical condition early Friday at the University of Alberta.

Shots were fired both inside and outside HUB Mall at the U of A just after midnight.

Police believe a G4S Security armoured car was the target of the robbery attempt.

Travis Brandon Baumgartner, 21, is a G4S employee believed to be one of several armoured company employees that were making a delivery to a bank located inside HUB Mall.

Baumgartner is the owner of a dark blue Ford F-150 pick-up truck with Alberta license plate ZRE 724.

Police urge the public to use extreme caution if they come in contact with Baumgartner.

EPS, RCMP, Canadian Border Services Agency and US Customs are looking for the man.

Police say two men and one woman were fatally shot inside HUB Mall during the attempted robbery.

One man was shot outside the mall and sent to hospital with life-threatening injuries.

The four victims were all G4S employees.

"We are dealing today with what can only be described as a horrific act of violence," said Police Chief Rod Knecht.

Two vehicles have been recovered – a van at the scene of the crime and an armoured vehicle was found just after 3 a.m. around 47 Street and 93 Avenue.

"It was an apparent armed robbery of armoured vehicle and or vehicles," said EPS spokesman Scott Pattison.

"The university was quickly put into lockdown, it has its own protocols and it remains in lockdown now. It's a crime scene so students are required to remain in their dorms."

Pattison says no students were involved in the incident.

Ravedh Seeberath was studying at Hub Mall at the time of the shooting.

"I heard what I thought at the time was fire crackers." said Seeberath.

"Later on I heard some commotion and I heard a lot of loud shouting. I also heard someone else shouting it was almost in agony – in pain – maybe a South east/South Asian/or Chinese accent and we all stayed back."

"I was walking back to where I was studying and that's when about 30 or 40 tactical members were rushing towards me with their automatic weapons, shot guns and dog."

Seeberath was told to leave the building after being interviewed by police.

The University of Alberta remains open to students Friday except for Hub Mall.

Anyone scheduled for an exam has the option of writing or deferring to a later date.

The U of A is offering counselling to students affected by the tragedy.

Counsellors are available at Lister Hall.

"Our first priority remains ensuring the safety of our students and providing support for everyone in the University community that has been touched by this tragedy. The safety of our faculty, staff and students remains our first priority," said Carl Amrhein, U of A provost.

Mayor Stephen Mandel issued a statement on Twitter Friday morning.

"Condolences to everyone touched by the fatal robbery/shooting at #UAlberta. Our thoughts and prayers are with you. #yeg #senselesstragedy."

G4S says they are devastated by the incident.

"The employees in Edmonton are quite devastated and really all of our employees across Canada are really feeling struck today," said Robin Steinberg with G4S.

"I think everyone is in shock."

They say it's the first on-the-job fatality the company has seen in Canada.

Counsellors are being provided to Edmonton employees.

G4S says about 100 people work in the Edmonton armoured vehicle branch.

"It's very tragic and our hearts go out to the families of the victims and all of our employees," Steinberg said.

The incident has sparked questions surrounding the university's emergency notification system.

The U of A's emergency notification was not activated until around 6:20 a.m.

The university made the decision not to issue a notification earlier – based on communication with the Edmonton Police Service, because the shooter or shooters were believed to be away from the scene early on.

However, many University of Alberta students took to social media to question the lack of notification.

"How can you tweet and not send out an emergency text? It's finals and I was on campus studying and I bet I'm not the only one," @jennnboo tweeted at 3:19 a.m.

"Nobody was notified. I live in HUB and I SAW this going on. I kept on waiting for something on my phone but NOTHING," tweeted @ai_siterul at 3:40 a.m.

"Can't believe there was a shooting at #ualberta last night. Also, a little surprised I received no emergency texts/emails," @KentonHam tweeted at 7:22 a.m.

Police ask anyone with information to contact the EPS complaint line at 780-423-4567 or Crime Stoppers at 1-800-222-TIPS (8477).