A dangerous, escaped prisoner is on the run in Nova Scotia and correction officials are still not sure how he managed to free himself from double-locked leg shackles and escape from custody.

Jermaine Carvery, 30, was being held on charges including attempted murder and hostage taking, when he bolted from a corrections van as he arrived at a Halifax hospital for day surgery.

He managed to outrun two unarmed corrections officer, who lost Carvery in less than 10 minutes.

Fred Honsberger, the province's executive director of correctional services said he was baffled by Carvery's escape.

"We still don't know how he did it," he said. "It's a mystery. I've never heard of anyone getting out of leg irons before.''

The still-locked leg-shackles were found in the van or near it, investigators said.

Honsberger said it was unlikely Carvery had anything on him to assist in escaping, as prisoners are searched before being moved. He declined to speculate if Carvery somehow managed to slip his ankles out of the irons.

He also said video footage showed both the leg shackles and handcuffs being put on the prisoner before he was moved.

When asked if the officers were fit enough to keep up with their prisoner, Honsberger only said they were "in reasonable shape."

Two corrections officers were assisting in the transfer, as per department policy, but the other officer was inside the hospital to get Carvery a wheelchair, at the time of the escape.

Carvery had handcuffs on him when he escaped, but police said those handcuffs were found across the street from the hospital - meaning he managed to get them off very early into his escape.

How the prisoner managed to escape wasn't the only question that was being asked of Honsberger, as it seems that corrections officers took 10 minutes to phone police about the escape - and they first phoned the jail, before notifying the police,

Originally, corrections officials said their officers took 25 minutes to make the call to police but Honsberger tightened up that gap today.

He now says Carvery escaped at 1:28 p.m., not 1:15 p.m. as was previously stated. Police received a call about the escape at 1:39 p.m.

"We're concerned about that loss of time and are looking into it," Honsberger said.

But police and corrections officials disagreed on how long it took police to assist in the pursuit, as Honsberger says it took police seven minutes to arrive.

But Halifax Regional Police spokesperson, Const. Jeff Carr said a police cruiser was on site within a minute.

Carvery was still at large Friday, although police said they had received a number of tips.

Carr said over 25 members, mostly plain-clothes officers, were assisting in the search.

Criticism

Bill Estabrooks, the NDP's justice critic, called for an independent review of the corrections system, saying it's the fourth miscue by corrections officers in the last four months.

"That would be a real good first step in restoring public confidence in correctional services in this province,'' he told The Canadian Press. "We don't need another internal review.''

In December, a man charged with assault was mistakenly released from the Dartmouth centre. The following month, a rape suspect was accidentally set free from a jail in Cape Breton. And later that month, another mix-up in Dartmouth led to the premature release of a man charged with aggravated assault.

Considered dangerous

Carvery is charged with a number of violent, high-profile robberies going back to 2004.

In one, masked thieves bound and gagged 42 Halifax Costco employees for more than two hours before escaping with a quantity of cigarettes estimated to be worth about $250,000.

Carvery is charged in three other thefts ranging from 2004 to 2006 that share some of the characteristics of the Costco robbery.

Police warned the public to consider Carvery dangerous and not to approach him.

With a report from CTV Atlantic's Rick Grant and files from The Canadian Press