Four people were injured when at least one shooter opened fire inside an apartment building in Whitby Thursday afternoon but police say they are still trying to piece together the events leading up to the incident.

The shooting happened inside an apartment building on White Oaks Court at around 12:30 p.m. Thursday.

Sgt. Nancy Van Rooy told reporters that the entire building was being treated like a crime scene.

Detectives are searching all 17 floors of the building, she said, but couldn't confirm whether there was more than one area in the complex where shots were fired.

"There are a number of occurrences prior to victims being struck," Van Rooy said during the news conference. She later clarlified her comment by saying that police had received several tips from witnesses and that investigators were following up on all of them.

A CP24 viewer emailed the newsroom with a photo of what was described as bullet holes in the elevator.

Critical injuries

Van Rooy said three of the victims were taken to a local hospital with serious but non-life-threatening injuries. A fourth victim was also rushed to that hospital but has since been airlifted to a trauma centre in downtown Toronto in critical condition.

That victim is 19 years old, according to authorities with ORNGE air ambulance. All of those injured are male.

Investigators have set up a perimeter around the crime scene as officers scour the area for evidence and search for suspects. That perimeter will be there throughout the day but Van Rooy said people should expect it will be there until detectives complete their initial investigation.

Officers are also looking to speak with anyone who may have witnessed the shooting.

No arrests have been made in connection with the shooting and police have not released any information about possible suspects.

Toronto connection investigated

Meanwhile, in Toronto, a man walked in to Rouge Valley Health Sciences Centre with a minor gunshot wound.

Police say a bullet grazed his stomach.

Van Rooy said Durham police went to the hospital to speak with the man to try and determine if there is any connection to the shooting in Whitby.

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