Travis Baumgartner, the man accused of shooting three fellow security guards to death and critically wounding a fourth in an apparent armoured car robbery, has been returned to Edmonton.

Baumgartner, 21, faces three counts of first-degree murder and one count of attempted murder. He was arrested on Saturday afternoon while attempting to enter the United States near Abbotsford, B.C.

An RCMP plane landed at Edmonton's City Centre Airport just before 2 p.m. Baumgartner was taken downtown to the Edmonton Remand Centre.

Matthew Schuman, a G4S guard and a corporal in the Canadian military, remains in critical condition. (Family)

He is scheduled to make his first appearance in court Thursday morning at 9 a.m.

The shooting, which took place early Friday morning in Hub Mall on the University of Alberta campus, killed Michelle Shegelski, 26, Brian Ilesic, 35 and Eddie Rejano, 39.

Matthew Schuman, the lone survivor of the attack, sustained head injuries and he remains in critical condition. His wife said Tuesday that she is hopeful his condition will improve.

Travis Baumgartner was detained at the border crossing near Abbotsford B.C. on Saturday. (CBC)

"Sunday evening was the first time that he opened his eyes and squeezed my hand," his wife Jennifer, who does not want her last name used, said in a written statement.

"Shortly thereafter, he went back to sleep. We remain cautiously optimistic that his condition will improve."

The victims and the accused were all working as armoured car guards for G4S at the time of the shooting. They were putting cash into a bank machine when the attack took place.