Police said first responders were called to a residential complex in the McCowan Road and Steeles Avenue East area at around 5 p.m. on June 14.
Investigators said two men carrying handguns got out of a vehicle and began firing shots at a man who was at the playground with a young child.
Two sisters, aged five and nine, were shot and rushed to the Hospital for Sick Children with serious injuries.
Police said the older sibling was shot in the leg and the younger one was shot in the abdomen. Both required multiple surgeries and are now at home recovering.
Authorities said at least 10 rounds were fired at the intended target where around 11 children were also playing.
Police said they were able to locate the vehicle involved in the shooting and the driver in Pickering just east of Toronto, 18 hours after the shots were fired.
The driver, identified as 21-year-old Sheldon Eriya, was arrested and charged with two counts of attempted murder as well as several other charges.
Canada-wide warrants were issued a week later for two more suspects identified as 23-year-old Tarrick Rhoden and 23-year-old T’Quan Robertson.
Both were wanted on suspicion of attempted murder, two counts each aggravated assault, and discharge of a firearm with intent.
Police said Rhoden was arrested on Wednesday and charged with 12 offences including attempted murder, two counts of aggravated assault and two counts of unauthorized possession of a firearm.
The third suspect, Robertson, remains at large. Rhoden is scheduled to appear in court on Thursday.
Police said a fourth suspect, identified as 59-year-old Vern McPhail, was also arrested. He is charged with accessory after the fact to commit an indictable offence.
Investigators said they have yet to identify and speak with the man initially targeted in the shooting.