WHITBY, ON -- Gunfire erupted over the noon-hour Thursday at an apartment complex with a checkered past, leaving four young men wounded, one of them fighting for his life.

Durham Regional Police are tight-lipped so far about the Toronto area's latest frightening outburst of gun violence, but the few details they have released suggest it was quite a chaotic scene inside 101 White Oaks Ct. -- one of four highrises west of Dundas and Brock Sts.

"The shooting happened in numerous locations," Sgt. Nancy van Rooy said, adding the entire building is considered a crime scene.

She said the bullets started flying around 12:30 p.m. and dozens of officers responded, including their K-9 and tactical units.

The four victims -- all young black males, according to residents who saw them taken away by paramedics -- were found inside the building.

One man, believed to be 19, was airlifted to a trauma centre in Toronto.

Van Rooy said he is listed in critical condition.

The injuries suffered by the other three victims are not considered life-threatening, she said, adding they were all treated at a hospital in Durham Region.

None of their ages have been officially released.

"We were not able to locate the suspect or suspects involved in this shooting," van Rooy said. "No arrests have been made but there are a number of leads that we are following up on."

She would not say if any guns had been recovered at the building or if it was a shootout.

Residents said at least part of the shooting occurred in the hallway on the seventh floor and bullet holes were reportedly found in an elevator.

One tenant told QMI Agency a friend on the floor of the shooting said he "heard four gunshots and then he saw some guy pushed back into the elevator, then the elevator went down to (the basement), then some girl starting screaming bloody murder down on (the basement)."

The resident was watching the closed-circuit broadcast of the lobby and she saw four black men taken out of the building on stretchers.

The resident added an "old lady" lived in the apartment closest to where the shooting happened with her kids, believed to be between the ages of 19 and 30, as well as her grandchildren.

"It's not a good situation. I hope none of the kids were home today."

Police are canvassing the building and the continue to hunt for the gunman or gunmen involved.

Van Rooy said homicide detectives are "overseeing" the investigation.