Peel regional police have cordoned off a house on Full Moon Circle in Mississauga, Ont., where 17-year-old Shadi Taleb was found without vital signs late Monday. (CBC)

Seventeen-year-old Shadi Taleb was killed and his mother badly injured when they were attacked outside of their Mississauga home on Monday night.

Police said the teen was found outside of a home on Full Moon Circle near Eglinton Avenue and Highway 403.

Officers went to the home after someone called for help at about 10:30 p.m. ET.

When they arrived, the teen had no vital signs and was rushed to hospital, where he was pronounced dead, Const. Adam Minnion said Tuesday.

Minnion did not specify the nature of the injuries to the teen.

His mother, 45, was also taken to hospital, but her injuries were reported to be minor — a bruise to her face and an eye injury.

The woman's name has not been released.

News reports Tuesday indicated the mother had told family members she had a gun held to her head during the incident — and that the family believes they were the target of a home invasion.

Police have refused to comment.

"Really what happened is still a bit of mystery for us as we try and piece this together," Minnion said.

Police did say they are looking for as many as five suspects in the slaying.

Minnion said investigators may eventually find a home invasion occurred, "but certainly at this point of the investigation, the evidence does not suggest that."

Police have not revealed any other details about the circumstances surrounding the killing, other than to say they are investigating and believe the suspects "may have left the scene in a light-coloured four-door vehicle."

An autopsy on the dead teen will be performed on Wednesday.