Illinois police arrested a child under the age of 17 Wednesday after two people were shot dead in a possible vigilante attack during a protest in Kenosha over the police killing of a black man, Jacob Barnes.Commander Norman Johnson of the Antioch Police Department said the suspect, a young man whose name was not revealed because he is under 18 , he was arrested on suspicion of intentional first-degree homicide. Police did not immediately release any other details. Antioch is about 15 miles from Kenosha, who has witnessed three nights in a row of riots since Blake was wounded by police over the weekend. The two people were killed Tuesday night in an attack by a young white man who was caught in a cell phone video opening fire in the middle of the street with a semi-automatic rifle.» I just killed someone,» he could be heard saying at one point during the shooting that it erupted just before midnight. In the wake of the killings, Wisconsin Gov. Tony Evers authorized 500 National Guard members to support local police in Kenosha, doubling the number of troops sent. The governor’s office said he was working in other states to bring in additional National Guard troops. and law enforcement officers. One victim was shot in the head and the other in the chest, Sheriff David Beth told the Milwaukee Journal Sentinel. A third person suffered gunshot wounds that are not believed to endanger his life.» We all yelled ‘The lives of blacks matter’ at the gas station and then we listened, boom, boom, and I said to my friend, «That’s not fireworks,» 19-year-old protester Devin Scott told the Chicago Tribune. And then this guy with this huge gun walks past us in the middle of the street and people yell, ‘He shot someone! He shot someone! And they’re all trying to fight the guy, chasing him and then he started shooting again.» Scott said he was stabbing a lifeless victim in his arms, and a woman started doing CPR, but «I don’t think he made it.» According to witness accounts and video footage, police apparently allowed the young man responsible for the shooting to pass by them with a rifle to the shoulder as members of the crowd shouted to arrest him because he had fired people. The sheriff told the Journal Sentinel that armed people had been patrolling the city streets in recent nights, but did not know if the attacker was among them.