Police allege that a man went to a home in the College and Huron area early Monday morning, and then "dispensed propane gas into the home while four occupants slept."
The man left, but soon returned to the same home, at which point he was discovered by two of the occupants who woke up, police say.
The man fled the scene but was later apprehended by police in the area.
CBC News has learned that the home is a residence for a group of Dominican Friars. The friars are a Roman Catholic religious order of preachers.
The home is located next to a daycare.
Police say the motive for the alleged acts is not yet clear.
However, Rev. Marcos Ramos, one of the men who lives in the home, told CBC News that another occupant had a connection to the accused.
"The person knew somebody in our community years ago, used to work with this person on some project before," Ramos said Monday.
"That’s the only thing I know, there’s only one person in the house who knew who this guy was."
A 53-year-old Vaughan, Ont., man now faces 15 criminal counts, including four counts of attempted murder and four counts of attempted arson.