Winnipeg police investigate the death of a teenager who had been stunned with a police Taser. (CBC)A 17-year-old boy who died after Winnipeg police officers fired a stun gun at him Tuesday was a suspect in a theft who refused to put down a knife when ordered, police said Wednesday.

Two citizens flagged down police officers about 4 p.m. Tuesday afternoon, saying they were following someone they had seen stealing property from a vehicle parked in the 1100 block of Notre Dame Avenue.

Officers located a suspect in the area behind a house in the 800 block of William Avenue, near Arlington Street.

The teen was "brandishing a knife," police said Wednesday, and refused to obey repeated commands to put the weapon down.

"That poses a threat to the officers, that poses a threat to other members of the public, and officers made the decision to deploy the electronic control device to ensure public safety as well as their own safety," said police spokeswoman Const. Jacqueline Chaput.

One officer deployed a Taser. The teen was admitted to hospital in critical condition and died shortly after.

First Taser-related death in Winnipeg

The cause of death has not yet been determined, police said. An autopsy is being conducted. It's not yet known if the teenager was intoxicated or had a pre-existing medical condition, Chaput said.

The suspect was alone and no other suspects are being sought, police said. Chaput could not say if he was previously known to police.

Police did not release the teen's name, but said his family had been contacted by police.

Larry Crisostomo, who lives near the area, told reporters he saw eight officers and a couple of paramedics working on a person on the ground.

"All I saw was a bunch of cop cars, ambulance, fire truck. They were all huddled around some guy, trying to revive him, and they had to give him the paddles," said Crisostomo.

'An electronic control device was used on a male by one of our officers,' said Winnipeg police Const. Jacqueline Chaput. (CBC)Other witnesses said they saw someone being chased down the lane just before police arrived, and some reported he was wielding a knife.

Winnipeg police have been using Tasers since September 2006, but this is the first time there has been a death related to their use.

Two officers are on administrative leave, which is protocol for the situation, Chaput said. Tasers are still being used by officers on the force, she said.

Taser use recently reviewed

Last October's death of Polish immigrant Robert Dziekanski at the Vancouver airport after he received at least two stun-gun jolts triggered debate over police use of the electronic device.

Dziekanski's and other high-profile deaths in the past months have prompted a closer look at the weapons and restrictions in at least one province, Nova Scotia.

'The Taser does have a legitimate purpose, however, we're concerned that there hasn't been adequate study.'— Hilary Homes, Amnesty International

Winnipeg's protection and community services committee asked police earlier this year for a review of the force's policy on the use of the devices.

"Based on what we heard from our police chief, it seemed to us — and still does seem to us — that our people are adequately trained and our protocol for use is supportable and reasonable in the context of the Winnipeg theatre," committee chair Coun. Gord Steeves said Wednesday.

"Personally, what I'm hoping is as the investigation of this incident goes through that it turns out that our people abided by all the protocols and that this was just an unfortunate incident."

A March report said the force had 150 Taser X26s in use. The model emits a 50,000-volt charge.

Police officers fired their Tasers 103 times in 2007 — 55 times using the probes, and 48 times in "drive stun" mode, in which police remove the probes and use the Taser directly on individuals.

Safety research needed, rights campaigner says

The Winnipeg case is believed to be the 22nd fatality following the use of a Taser in Canada since 2003.

Amnesty International Canada has been calling for a moratorium on the devices until more independent safety studies can be done.

"The Taser does have a legitimate purpose, however, we're concerned that there hasn't been adequate study, " said Hilary Homes, a security and human rights campaigner for the group. "We really don't know enough about the effects to judge the acceptable risk and the acceptable parameters for use."

A handful of probes began after Dziekanski's death. A House of Commons public safety committee is studying the growing use of stun guns in Canada.

In June, the RCMP watchdog released a report recommending that members of the force with less than five years of operational experience should be prohibited from using stun guns and that anyone zapped should receive immediate medical attention.