Toronto police Chief Bill Blair says people "have every right to be concerned" after an 18-year-old man armed with a knife on a downtown streetcar was shot repeatedly and killed by police this weekend — an incident captured by amateur video. Blair said he has seen the video, which was posted online. "I am very aware that the public is very concerned about this tragic event," he told media in a prepared statement. "They have every right to be concerned." Witnesses say Sammy Yatim was alone on the 505 Dundas streetcar near Trinity Bellwoods Park when he was shot just after midnight ET Saturday morning. He had pulled a knife and ordered everybody off the streetcar, witnesses say. The video shows the stopped streetcar at a distance, with multiple police officers nearby, at least one with his hands raised to shoulder height. Nine gunshots are heard within 13 seconds. Blair said he knows the public has many questions after seeing the video. "I am also seeking answers to those important questions," he said. He promised an "unwavering commitment" to finding them. The chief said he has asked deputy chief Mike Federico to reach out to the family. "As a father, I can only imagine their terrible grief and their need for answers," Blair said. Police watchdog probing shooting Blair did not take questions, noting that he is forbidden by law to interfere with the investigation of Ontario's police watchdog, the Special Investigations Unit. "I regret that I'm unable to answer any of your questions," he said. "The law is rather clear with respect to that." The SIU has begun an investigation of the incident, as it must under provincial law, and Blair promised to co-operate fully. The chief said there will also be an internal investigation. Blair said he is required by law to review the policy, procedures and training of the service, and to see if they were followed. A full report of the chief's review must go to the police board within 30 days of the SIU's report going to the province's attorney general. On Monday, the SIU issued a news release updating the public on the status of its investigation into the shooting. The release said that Yatim sustained "multiple gunshot wounds" in the incident and also indicated that police had also used a stun gun. The SIU said that it has identified a single subject officer and 22 witness officers. The Ontario ombudsman also said in a tweet Monday that his office will be "reviewing" the shooting on Tuesday. Ontario Premier Kathleen Wynne said it was a tragic situation and that her heart went out to the family, but that she couldn't say more given the ongoing investigation. On Twitter, Mike McCormack, the president of the Toronto Police Association, called on the public to wait for the results of the SIU investigation "before coming to conclusions" about what happened. McCormack also tweeted that "police shootings are a tragedy for all involved," and extended condolences to Yatim's friends and family. Security expert concerned Ross McLean, a security expert and former Toronto police officer, studied a version of the video with enhanced video and audio, frame by frame. He said it raises serious questions about how police handled the confrontation. On the enhanced video, a six-second jolt from a Taser can be heard after the gunshots, McLean said. Yatim also appears to put his hands over his head at one point on the enhanced video, he said. McLean says if the officers had waited another minute for the officer with the Taser to arrive instead of opening fire, Yatim might be alive today. "Should you be Tasering someone who’s been shot six or nine times and lying on the ground?” he told CBC News. McLean says the video also suggests police did not engage the suspect. "Your mouth is your best weapon," he said. The key is to communicate with and contain the suspect, he said. "He was fairly contained. He was in the streetcar. He could have let that guy sit there all night." Police can be heard on the enhanced video saying "Drop the knife!" and "If you take one step in this direction, you’re finished," McLean told CBC host Matt Galloway on Toronto's morning radio program Metro Morning. McLean said it's unlikely that any of the nine shots were warning shots. "This officer’s going to have to explain why he used the level of force he did," McLean said. Vigil today A vigil for Yatim has been planned for 5 p.m. today at Yonge-Dundas Square in downtown Toronto. The family, which moved to Toronto from Syria about five years ago, is hiring a lawyer and wonders how police could shoot him multiple times even after it appears he went down. His sister, Sarah, said her family is in shock. Yatim's friends have posted their condolences for the recent high school graduate on social media, and Sarah has started a Facebook group that she hopes will help stop what she considers an injustice at the hands of police.

I live about 30 mins from the shooting place. The Investigation shut off any information from leaking, they already know they screwed up. Many people that knew the boy (he was 17, not yet 18) not sure why he had a knife, he was normal(if you were to describe someone you know). The knife: it was a 3 INCH knife. during the shooting, he was not a threat to anyone, he had his hands to the side, NO ONE WAS AROUND. All they know is the police officer just opened fire for no reason. The bystanders did not expect police to shoot, let alone 9 times. The bystanders didn't even think it warranted a gun. The person with a knife was just standing, no threat to anyone, did not move toward the police. This is all the info i have so far. The media is keeping a VERY CLOSE LID on it, only information that are leaking is from the family and friends.

Witnesses say Sammy Yatim was alone on the 505 Dundas streetcar near Trinity Bellwoods Park when he was shot just after midnight ET Saturday morning. He had pulled a knife and ordered everybody off the streetcar, witnesses say.

Originally posted by Amaru He should have dropped that knife like they told him to.

1) There was nobody on the bus at the time, contrary to what reports are saying

2) He had a little 3 inch knife

3) Instead of tapering him first, they shot him 5 times in the chest, then tazered him, followed by another 5 shots.

It's pretty sad considering he came over here with his father because Syria was unsafe, and then he was killed by POLICE for no reason. This is why Torontos so ****ed up. We need a major ****ing reform. Back in like late May, a man in Hamilton (another major city not to far) a man climbed over a highway sound barrier to get his shoe. He was in a fight with his wife, and the police got called, and they told him to climb back over. Supposedly they had misidentified him, so they shot him multiple times on his front lawn until he died. I mean the guy had a little girl on the way and a wife? The police got away scot free. It's disgusting how much power police can have. RIP to that young man

Originally posted by Amaru He should have dropped that knife like they told him to.

According to some witnesses, Yatim threatened some female passengers with a knife in one hand and his penis in the other.

Originally posted by Pie-kun There was something seriously not right with this kid.

Originally posted by Pie-kun There was something seriously not right with this kid.

Originally posted by JonnyϟLightning He should have followed orders. The cop acted accordingly. He was a threat.