CHICAGO (WLS) -- A man was charged in the fatal shooting of a 2-year-old boy on Chicago's Northwest Side earlier this month Julian Gonzalez, 2, and an 18-year-old man were shot just after 10:15 p.m. on Oct. 6. They were on a sidewalk near the mouth of an alley in the 2200-block of North Kilbourn Avenue when shots were fired their direction.Police said that Alexander Varela, 27, got involved in a physical altercation at a birthday party and ordered another man to fire into a group of people. The entire incident stemmed from what police called "a simple and petty argument from individuals who live on the block.""This was a birthday party, OK, so people were celebrating when this occurred," Chicago Police Deputy Chief of Detectives Brendan Deenihan said. "There was a petty argument between a couple of women and this offender, who lives on the block, who is a gang member. He chose to insert himself into the argument, OK. He wasn't at the party. He wasn't invited to the party. There's always little squabbles, but he's a gang member and he thinks he owns the block. So he's going to come down there and insert himself into the argument."Authorities said Varela walked up to party-goers and demanded to know their gang affiliations. After they said they weren't in gangs, other gang members allegedly started making threats to kill them. That's when the fight turned physical.Varela allegedly shouted, "Bust, bust, bust!" and gave the command to shoot. Authorities said the firearm used by the gunman had laser sight attached to it.The 18-year-old man was shot in the back and twice in the leg. He told police he noticed Julian as he ran from the gunfire. Authorities said the 2-year-old had left his home through a back gate and was walking down the alley. When the 18-year-old victim noticed him, he tried to protect him.Julian was shot in the neck. He was transported to Stroger Hospital, where he later died.The 18-year-old man was transported to Illinois Masonic Hospital, where his condition stabilized.Police said Varela is known gang member. He was charged with first-degree murder. Investigators said witnesses from the party led them to Varela.He was not granted bail Monday. Varela is due back in court Nov. 9.In announcing the charges Monday, detectives made it clear that the investigation was still open. The shooter is not yet in custody.