Toronto police are concerned about possible retaliation in the wake of one of the worst incidents of gun violence in the city’s history, which left two people dead and another 23 wounded.

Shooting erupted at a block party in a Scarborough neighbourhood on Monday night, which police believe was attended by at least 100 people. The shooting left crowds of people fleeing the neighbourhood near Morningside Avenue and Lawrence Avenue East, as police arrived at the scene.

Police soon determined that two people were dead and nearly two dozen others were wounded in the spray of bullets. One person was trampled as panicked partygoers fled the scene.

Det. Sgt. Graham Gibson identified the deceased during a news conference on Tuesday afternoon as Joshua Yasay, 23, of Ajax, Ont., and Shyanne Charles, 14, of Toronto.

It is not clear if gangs were involved in the shootings, but Chief Bill Blair said police are investigating that possibility.

He said police are also "very concerned" about the potential for retaliatory violence following the Danzig Street shooting.

"The crime that occurred in Scarborough yesterday was unprecedented for the city of Toronto," Blair said.

"It is a crime that is shocking to all of our citizens and it is a crime that demands the relentless pursuit of the individuals responsible for this violence."

The surviving victims of the Monday night shooting ranged in age from a 22-month-old toddler, who received a “grazing injury,” to a 33-year-old man, Blair said.

While most of these victims are expected to recover, one man remains in critical condition in hospital as of Tuesday morning.

Blair said the homicide squad, the guns and gangs unit, the intelligence services urban gang unit and divisional policing are all involved in the investigation.

"We will be deploying significant, additional uniform resources into the community affected and to any other area where we believe retaliatory violence may take place," Blair said.

Dispute prompted shooting

Police believe that at about 10:40 p.m. on Monday, two individuals got into a dispute at a block party that was being held on Danzig Street.

Blair said that the "altercation involved two individuals and as a result, there was an exchange of gunfire."

Police previously confirmed that more than one weapon was fired and that a gun had been recovered at the scene.

Blair said police have also identified one person of interest.

The party had been billed on Twitter as a "Hennessy party" where Hennessy cognac would be available for free.

Earlier in the day, community resident Shannon Longshaw said she had organized a neighbourhood party for children that was scheduled to end in the evening.

"I don't know who those people [are] who actually came," she said. "I had a small things for kids in the community."

Resident Shelly Dupuis told CBC News she estimated the crowd at the later party was between 200 and 250 people.

'It scares the hell out of me'

Dupuis said she was sitting in her backyard on Monday night when she heard a series of “eight to 10 shots” fired.

“We came running through the back door, out through the front door, and there's people running everywhere screaming,” Dupuis said.

"People holding their kids, picking up their kids off the ground. People running everywhere …and then I come around the corner and there's lights. Wall to wall lights. I've never seen this many ambulances ever.

"It scares the hell out of me. It was about 10 houses down from where we live and my child could have been out there. My child could have been the one that got shot."

Shyanne Charles, 14, was pronounced dead on the scene of the shooting on Danzig Street late Monday. (Twitter)

While police have made contact with some witnesses, Blair asked that anyone with information come forward to help investigators.

"In order to ensure that we very quickly bring this matter to a resolution, we are asking for the public’s help," said Blair.

Gibson added to that appeal on Tuesday afternoon, saying that the people who saw what happened can help make their city safer by working with police.

Police believe at least 100 people attended the party where the shooting occurred, Gibson said.

Torontonians must 'carry on'

Toronto Mayor Rob Ford toured the scene of the Scarborough shooting on Tuesday morning.

Joshua Yasay, 23, of Ajax, Ont., graduated from York University with an honours BA in criminology in June 2011.

While denouncing the violence, the mayor said that the city and its residents would have to "move on and carry on with their life" as police deal with the challenge of apprehending those responsible for the Monday night shooting. Later in the day, the mayor released a statement blaming the violence on gangs.

"There is no room in Toronto for violent gangs," the statement said.

Ford said he will work with Premier Dalton McGuinty and Prime Minister Stephen Harper to combat gang violence.

"We must use every legal means to make life for these thugs miserable, to put them behind bars, or to run them out of town," he said. "We will not rest until being a gang member is a miserable, undesirable life."

Victim had degree in criminology

One of those killed Monday night was Yasay, who graduated with an honours BA in criminology in June 2011, a spokesperson from York University in Toronto confirmed.

The other was Charles, a teenager who lived in the area and who had recently graduated Grade 8. Friends described her as a generous person, a good student and a role model.

A vigil held in the area on Tuesday night drew a number of mourners who gathered to remember those killed in the shooting. Some carried flowers, others held candles and many shed tears as they stood in small groups.

Police have been dealing with a sharp increase in the number of shootings in the city of Toronto this year compared with last.

According to preliminary statistics posted on the police website, there were 140 reported shooting incidents as of July 16.

That’s an increase of 32.1 per cent compared with the number reported at the same time last year.

Prior to the shooting on Monday evening, 16 people had been killed in gun-related homicides on the streets of Toronto since Jan. 1, compared with 14 people at the same time last year.

Danzig Street, Toronto, Ont.

The Monday night shooting in Scarborough was also the latest event in which a gun was fired in a crowded space.

A shooting at the Eaton Centre on June 2 left one man dead and another fatally wounded.

Later that month, a man was shot dead on a crowded patio in Little Italy where patrons had gathered to watch a soccer game.

On Canada Day, a man was shot in the chest after the close of a fireworks show.

Ford said the recent high-profile shootings were "a couple of isolated and unfortunate incidents."

With files from The Canadian Press