Toronto police homicide investigators are asking the public to help identify two "persons of interest" after a man and woman were killed in two separate brazen shootings at the Muzik nightclub.

Homicide Insp. Peter Moreira said gunfire erupted at the nightclub around 3:20 a.m. Tuesday, where some 4,000 people were attending an after-party for Toronto rapper Drake's OVO Fest.  

Moreira revealed little about the two persons of interest, but described them both as young men. 

The first man is described as a black male, six feet to six feet one inch tall, about 25 or 26 years old with a fresh buzzcut. He was wearing a purple crewneck sweater and dark blue jeans.

The second man, who was last seen near the Dufferin Gates, is described as a brown-skinned male, five feet 10 inches or five feet 11 inches tall with a skinny build, between 24 and 28 years of age. He was wearing a yellow and burgundy plaid button-up shirt.

Tuesday's violence consisted of two separate shootings, and investigators have yet to definitively link the two. 

Moreira said paid-duty officers raced into the club when they heard the first gunshots and found a male on the patio with gunshot wounds. He was later pronounced dead at the scene.

Two more victims, a man and a woman, were found with gunshot wounds just outside the patio's fence and were taken to hospital. Another male victim, who was believed to be at the club, made his way to Dufferin and College streets — about two kilometres from Muzik — before flagging down a passing ambulance for assistance.

As patrons fled the club, located at Toronto's Exhibition Place, there was a second shooting at the nearby Dufferin Gates. An officer on a bicycle was the first to respond and administer CPR to a female victim. She was transported to hospital, where she later died.

The woman who died north of the Dufferin Gates did not appear to have played a role in the events that led up to the gunfire, Moreira said.

Police have not yet identified either of the two shooting victims who died.

The other shooting victims who were hospitalized are expected to survive.

2nd year of shooting at OVO after-party

The shootings mark the second year in a row gunfire has marred the OVO Fest after-party. 

Police described Drake's annual festival at the nearby Molson Canadian Amphitheatre as well run, but said more officers were called as crowds swelled near the after-party. 

When asked whether Drake was in the club at the time of the shooting, Moreira said that was not included in the scope of the police investigation.

The rapper has not commented on the shooting, despite multiple requests from CBC News.

One man was hospitalized after a shooting last year outside the same event.

Police seek witnesses, pictures

Toronto police say they've spoken with an "extremely small percentage" of those who were in the club and urged people to come forward and help investigators figure out what triggered the violence.

Deputy Police Chief Peter Sloly

Toronto Deputy Chief Peter Sloly said there were extra officers deployed at the scene ahead of the shooting that killed two people. (CBC)

Police are asking anyone who took pictures or video at any time during the night to provide it to investigators. Moreira would not directly answer a question about surveillance cameras inside the club, except to say that video evidence is "always important" to an investigation.

As dawn broke over the area, police cordoned off an extensive crime scene, shutting down multiple streets in the area. 

One area resident said he heard two gunshots shortly after 3 a.m. "and it was just mayhem after that."

Deputy Chief Peter Sloly said that considering how packed the nightclub was, the shooting could have been worse.

​"We're lucky there wasn't a larger body count," said Sloly. "We have a brazen set of individuals who are willing to put lives at risk."

In a Twitter message, Mayor John Tory said he is "saddened and angered" by this "senseless shooting."

In a statement, the owner of Muzik expressed condolences for victims, and "praised the actions and professionalism of our entire security team."

"We're absolutely shocked by this horrific attack," said Zlatko Starkovski. "We are fully co-operating with Toronto police and have full confidence they will get to the bottom of this horrific incident, and bring these people to justice."