HALIFAX - Nova Scotia's Justice Department warned the public Thursday that a prisoner who escaped while he was being escorted to a medical appointment is considered dangerous.

Jermaine Carvery, 30, of Halifax, was being held on a variety of charges, including attempted murder and hostage-taking, at the Central Nova Scotia Correctional Facility.

Fred Honsberger, the department's executive director of correctional services, said the escape occurred as Carvery was being taken to the Victoria General Hospital in Halifax at about 1:15 p.m.

"He was being taken out of the back of the correctional worker's van,'' he said. "He somehow had escaped leg restraints while in the van and bolted at that point.''

Honsberger said two guards were making the transfer, which is in accordance with department policy.

He said Carvery managed to run by one guard who was opening the door of the van. The other guard was in the process of getting a wheel chair to take Carvery into the hospital when he fled.

No one was hurt in the incident.

Honsberger said an internal investigation into what happened is underway.

Meanwhile, justice officials are advising the public to stay away and call police should they encounter Carvery.

The charges against Carvery were laid after four violent armed robberies of retail outlets in the province, some dating back to 2004.

The high-profile crimes included a heist in July 2004 at a Costco outlet near Halifax. Masked thieves bound and gagged 42 employees for over two hours before escaping with a large quantity of cigarettes estimated to be worth about $250,000.

The theft was similar to one in April 2004 at a TRA Cash and Carry store in Truro, where three masked and armed suspects tied up three employees before fleeing with a quantity of cigarettes estimated to be worth $77,000.

In both incidents the thieves loaded a large truck with the stolen merchandise.

The third incident, in September 2004, saw a quantity of cash stolen from Chrissy's Trading Post in Hammonds Plains near Halifax. Three armed and masked men entered the store and restrained an employee. Two others were also restrained in the store's parking lot.

The fourth robbery occurred in September 2006 at ATM Direct Cash Group in Dartmouth. In that incident police said a shot was fired before two suspects made off with about $100,000 in cash.