Fawad Ahmed Nouri, 25, escaped from custody Tuesday morning in Hamilton, and is considered armed and dangerous. (Hamilton police)

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, 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 accomplices burst out of the hospital.

Supt. Bill Stewart said it appears planning went into the escape because prisoners aren't told when their visits to 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 outlet in Hamilton.

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

Two suspects, described as dark-skinned 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 accomplices and Nouri made their getaway, they hit an ambulance.

The men dumped the vehicle at the corner of Birge Street and Victoria Avenue North, then got into a silver Hyundai Tiberon, which was last seen heading east on Birge Street, police said.

The guards weren't seriously hurt in the altercation, police said.

Nouri is described as six-foot-one, 163 pounds.

Police are asking anybody with information about Nouri's whereabouts to call 911.

Nouri was arrested with another man, 26-year-old Todd Fenty, in connection with an armed robbery at a doughnut shop.

During that robbery, suspects exchanged gunfire with police and led officers on a high-speed chase.

Nouri was awaiting trial on several charges, including four counts of robbery and one count of wearing a disguise with intent to commit an indictable offence.

He has previous convictions for armed robbery.