HAMILTON, Ont. - Police were scouring the city of Hamilton for a prisoner on the lam after a daring and almost certainly planned escape that saw two masked and armed men bust him out of custody outside a hospital Tuesday morning.

Fawad Nouri, 25, was leaving Hamilton General Hospital in the late morning, escorted by two jail guards when the suspects burst out of the hospital.

Supt. Bill Stewart said it appears as though some planning went into the escape because prisoners aren't told when their visits to the hospital will take place.

"Obviously the persons who assisted in this escape were able to obtain some sort of information that allowed them to be there at that time," he said.

"It's not to suggest in any way that there was any inside information. It could have been a number of different things where they just got lucky, even."

Nouri was in custody at the Hamilton-Wentworth Detention Centre after being wounded in a shootout with police in January following an alleged armed robbery at a Tim Hortons.

He was at Hamilton General Hospital on Tuesday for a followup visit and two jail guards, one man and one woman, were escorting him out of the hospital's emergency area just after 11:20 a.m.

Two suspects, described as dark-skinned Middle Eastern men, clothed in hoodies and wearing surgical-type masks, burst out of the hospital carrying black handguns, Stewart said.

The men ordered the guards to the ground and fled with Nouri in the Ministry of Correctional Services van that was being used to transport the prisoner. As the suspects and Nouri made their getaway in the van off hospital grounds they hit an ambulance, then dumped the van a short distance away, Stewart said.

The men were then seen getting into a silver Hyundai Tiburon and heading eastbound. Police did not have information on that car's licence plate number.

Officers from several different units were involved in the search that during the day involved a perimeter set up in the city.

Nouri is described as Middle Eastern, six-foot-one and 163 pounds. He was last seen wearing an orange jumpsuit.

Police are warning the public not to approach Nouri or the other men as they are considered armed and dangerous. Police say people should call 911 instead.

The guards were physically uninjured and gave statements Tuesday to investigators.

"The guards weren't harmed, but they were certainly shaken up by the incident," Stewart said.

Stewart did not have a complete list of charges Nouri was facing prior to his escape, but he was allegedly involved in an armed robbery at a Tim Hortons and a subsequent police shootout earlier this year in which he was hit in the arm by a police bullet.

The province's Special Investigations Unit looked into the incident and found Nouri fired first at officers during a foot chase and concluded there were no reasonable grounds to believe the officers committed a criminal offence.

He was also known to police in Toronto, said spokeswoman Const. Isabelle Cotton, though she was not able to comment on specific charges or convictions.

Hamilton police told investigators in Toronto that Nouri has family in Toronto, so it's possible he may be making his way there, but there is no indication that is where Nouri is going, Cotton said.