UPDATE: - A teenager who was Tasered by police in London, Ont., was defending himself when he was hit by the stun gun, his mother said Friday.
But police said use of the shocking device was justified, in order to stop a fight between two 17-year-old boys as a crowd of other teens watched.
Can't see the video above? Watch it on YouTube.
Thursday's incident, caught on a cellphone camera and posted on YouTube, shows police approaching the altercation and a sergeant discharging a weapon.
Prongs from the Taser hit the boy in the ear and chest and he falls to the ground.
A bystander can be heard shouting that the boy had been shot without first being asked to stop fighting.
"Why would you Tase him? Why would you Tase him? You shot him in the head, you shot him in the head, you shot him in the head, bro," the male bystander yells.
"You shot him in the head, you never even asked him, you never even asked him to stop, you never even asked him to stop, bro," he shouts.
The sergeant was justified in deploying the Taser without giving a verbal warning, London's chief of police said Friday.
The teen had wrapped a belt around his fist, punched the other teen and then used a chair to strike the other teen about his head, Chief Brad Duncan said.
"Clearly here it was unfolding very, very quickly," he said.
"In fact, when one views the video, it's about a second between the use of force by this individual and then the application of the conducted energy weapon," Duncan said.
"Clearly at the time that the device was deployed, he was the aggressor."
The boy who was hit by the stun gun has been charged with assault with a weapon. The other boy, who goes to a different school, has not been charged and has been released from custody.
The mother of the teen who was shocked said her son was punched and kicked by two other teens and had used his belt and a lawn chair to defend himself from being hit.
He yelled to his girlfriend to call police as he was attacked, the mother said.
The fight started because one of the teens believed her son tried to pick up one of their girlfriends, she said.
The mother is upset police didn't issue a warning before using the Taser, which she said should only be deployed as a last resort.
Police said the teen was taken to hospital because of injuries sustained in the fight and was later released into police custody.
But the boy’s mother said he was treated for Taser injuries.
“EMS (are) the only ones who are able to remove the prongs from the Tasers and because of the location they couldn't remove the prongs,” she told London radio station AM980.
“It took three plastic surgeons to try and remove the prong from the side of his ear.
“They indicated that he was lucky that it wasn't two centimetres closer to the front of his face, because he would have had permanent paralyzing of his face.”
By Pat Hewitt in Toronto
Questions are being raised in London, Ont., after a police officer was videotaped breaking up a street fight by shooting a Taser at one of the teenage participants.
The teen is in hospital and high-school students are threatening a protest against police after the incident Thursday morning, The London Free Press reports.
A cell phone video of the clash was posted on YouTube. As the Free Press reports:
The images show one combatant hitting the other with a chair when an officer on foot hurries in from the street and shoots a dart from a Taser stun gun at a young man wearing jeans and a black shirt.
A witness, who said he was a cousin of the boy hit by the Taser, told AM980 there was no warning before police used the stun gun:
"They just rolled up out of the car and fired the Taser. He didn't warn him at all and shot him in the face, my cousin dropped and the cop still kept shocking him," he said.
Colleagues of the teen plan to protest Monday, NewsTalk 1290 reports.
In Canada, Tasers are a prohibited weapon. The CBC reports that only one company can import them into the country under a special permit and the devices can only be sold to law enforcement agencies.
The police use of Tasers continues to generate controversy in Canada. Earlier this week, a standoff involving Toronto police ended with a man falling nine metres from a balcony to the concrete below after he was hit by a stun gun. The man was rushed to hospital in critical condition. Watch video of the incident.
Last week, the public learned that RCMP officers who stunned an 11-year-old boy with a Taser in northeastern British Columbia won't face charges.
The child was shocked with the stun gun in April after several Mounties responded to a stabbing at a group home in Prince George.
Police forces are still grappling with the fallout of the death and public inquiry into the case of Robert Dziekanski.
Dziekanski died in Vancouver's airport in October 2007, when he was confronted by four RCMP officers and stunned multiple times with a Taser.
After a two-part public inquiry, commissioner Thomas Braidwood concluded Tasers can be fatal in rare circumstances, and he identified several factors that would increase that risk.
Among those most at risk, Braidwood wrote in one of his reports, were people with pre-existing heart conditions and children because of their smaller size.
London, Ontario is about two hours west of Toronto.
With files from The Canadian Press