Normal police operations have resumed in Toronto's downtown core following a heightened concern about public safety.

An "unconfirmed and uncorroborated" piece of information triggered increased police presence in the popular tourist area early Thursday morning.

Front-line Toronto police officers from multiple divisions flocked to vicinity while the unspecified threat was investigated. Police called off the extra security by 10:30 p.m.

“We know this heightened security can be concerning for the public,” the statement released late Thursday read. “Our goal is always to be as transparent as possible while protecting the integrity of our investigations.”

Police said citizens will continue to see an increased police presence around the Rogers Centre, but that the effort is part of their 2018 downtown security plan and not a reflection of the earlier concern.

Internal memo details 'threat' to CN Tower

A bulletin sent to Toronto police supervisors and shared with officers Thursday afternoon, which was obtained by CTV News Toronto, revealed the “unconfirmed and uncorroborated information” that triggered the increased police presence was “a threat to tourist attractions in the greater Toronto area including the CN Tower.”

The bulletin indicated that the information was received on Wednesday, but stressed that there has been no corroborating information and no details about the “identity of the perpetrator(s)” or any affiliation to extremist groups.

“Although there is no information on the nature of this threat, tactics employed by extremists have included the use of vehicles, small arms, knives and/or explosives,” the bulletin reads.

It also referred to an “operational plan” that advised of unsubstantiated threats regarding a potential vehicle ramming attack near the CN Tower.

Police later addressed the widely circulating memo, calling it an unapproved draft.

Moving company U-Haul later released a statement saying it was contacted by the Ontario Provincial Police on July 11 about the "suspicious activity" in the Toronto-area. The company was asked to “remain vigilant” and urged to report anything they deemed unusual. Vice President of Communications Sebastien Reyes said in a statement.

“As a result, and at the request of police, U-Haul issued a reminder to our Ontario team members to continue being mindful of suspicious behaviour and reiterated instructions on how to report such behaviour to police,” Vice President of Communications Sebastien Reyes said in the statement.

Insp. Michael Barksy said the additional front-line police officers were scattered throughout 52 Division as a result of the unspecified information.

The area, which is bordered by Spadina Avenue to the west, Bloor Street to the north, Yonge Street to the east and the waterfront to the south, encompasses popular Toronto landmarks such as the CN Tower and the Rogers Centre.

York Regional Police later confirmed that they too were monitoring several areas in their region.

Barksy was tight-lipped about the situation and would not divulge anything “investigative.”

“The only requirement from the police, we believe that is necessary, is enhanced police presence in this area,” he told reporters shortly before noon.

“Because it is a potential risk, it’s something that, from an investigative standpoint, we have to continue to monitor. If we could provide more specifics, we would certainly be forthwith with that.”

Despite the boosted security, Barksy said all businesses in the affected areas would remain open and that Torontonians should continue to enjoy the neighbourhood. He pointed to the concrete jersey barriers installed in typically-populated areas around the downtown core as an example of how police are constantly monitoring public safety.

A Foo Fighters concert scheduled for tonight at the Rogers Centre went ahead as planned.

“As you’ll see tonight with the Foo Fighters, we’ll have increased police presence and that’s for public safety," he said. "It’s not inconsistent with anything we’ve done in the recent past and it won’t be inconsistent with anything we do in the future.”

However, he asked residents who see something that seems “out of the norm” to contact authorities.

“Without the eyes of the public, we won’t succeed,” he said.

Major landmarks dotted with police officers

Video from the CTV News Toronto Chopper showed a number of cruisers near the Rogers Centre, the Scotiabank Arena, the Metro Toronto Convention Centre and Ripley’s Aquarium. Several officers with Toronto police’s Emergency Task Force were also spotted in the Bremner Boulevard and Lower Simcoe Street area.

An increased police presence was also confirmed at Canada’s Wonderland, which is located in Vaughan, about 30 minutes north of Toronto.

While the amusement park remained open, a spokesperson said York Regional Police officers were on-site as a result of the unspecified threat in the GTA.

York Regional Police Const. Laura Nicolle told CP24 they responded "immediately" after becoming aware of the information this morning. She said there were other locations outside of Canada’s Wonderland that officers were monitoring but would not say where.

Toronto police also tapped nearby 14 Division and 51 Division for assistance patrolling the downtown core.

The force was reportedly in touch with other police jurisdictions in the GTA but Barksy would not disclose specifics.

Toronto Police Association President Mike McCormack said police perform a “risk assessment” when deciding what information to release during an investigation. He said police often withhold some information for the sake of public safety.

“It is very critical in these situations that the investigation is protected, that the information, if there is a need, is protected. Some information you can’t let out, it would compromise an investigation,” he said.

“We’ve got a great group of intelligence officers and they are analyzing every bit of intelligence they have.”

City, province, feds all briefed on situation

Earlier Thursday, a spokesperson for Toronto Mayor John Tory confirmed that he was aware of the investigation.

“The Mayor was briefed by Chief Saunders this morning and he will be continuing to monitor the situation,” a statement reads. “We have no further comment at this time and all questions should be directed to Toronto Police.”

Premier Doug Ford, who laid out his priorities in his government’s first throne speech at Queen’s Park this afternoon, was also briefed by security officials.

“We are aware of the reported potential threat in the City of Toronto. While the information is unsubstantiated, the Premier has been briefed by the Provincial Security Advisor and is actively monitoring the situation,” a statement from his office reads. “Our officials remain in close contact with federal and municipal security partners.”

Minister of Public Safety Ralph Goodale also tweeted about the situation, saying “federal agencies are aware of heightened police presence in the GTA.”

“As per normal policing arrangements, (we) stand ready to assist if necessary,” the tweet, sent shortly before 11 a.m., reads.

While not involved in the investigation, the RCMP confirmed that they too were briefed about the situation.

-With files from CTV News Toronto's Tamara Cherry