Parliament Hill evacuation in Ottawa may have been prompted by hoax or bad tip, sources say

An investigation into a "potential threat" that led to the lockdown of Parliament Hill for a time was in its second day Sunday, after police in Ottawa determined there was no danger to public safety.

Police initially deemed that the threat Saturday afternoon was credible. Members of Parliament, senators and their staff were told to "shelter in place" as officers closed off streets while they investigated a "suspicious incident" and a "potential threat in the Parliament Hill area."

Since then, multiple sources briefed on the situation have told CBC News that police are now investigating whether the source of the threat was a hoax. They're also trying to determine if the tip that led to the massive police response was just a bad tip, according to the sources, who spoke on the condition they not be named because they're not authorized to go on the record.

The sources also say there's no threat to national security.

As of Sunday afternoon, police have not announced any arrests or charges. The sources said charges, if any, aren't imminent.

A senior government source briefed on the situation confirmed the initial tip for the "suspicious incident" was received Saturday afternoon from the intelligence branch of the Canada Border Services Agency (CBSA), a detail that was first reported by Global News.

CBSA warned the potential threat to the parliamentary precinct involved possible explosives in vehicles parked near Parliament Hill, the source said.

Law enforcement sources said the potential threat was treated as credible at the time and seen as serious. An investigation — involving the Ottawa Police Service (OPS), Parliamentary Protective Service (PPS) and the RCMP, among others — was launched.

At 12:55 p.m. ET, the notice to shelter in place was sent to all parliamentarians and parliamentary employees by PPS — which leads the security operations in the parliamentary precinct — alerting them to what the service called a "possible threat." Parliament Hill was also evacuated.

In Ottawa's downtown core, city police closed Wellington Street between Elgin Street and Bronson Avenue, as well as Metcalfe Street between Albert and Slater streets.

Senior government sources told CBC News that Prime Minister Justin Trudeau and Public Safety Minister Marco Mendicino were both briefed on the incident. At the time, Trudeau was in Los Angeles about to head back to Canada following the conclusion of the Summit of the Americas.

By 3:35 p.m., police tape that blocked access to Parliament Hill started coming down.

"Following an investigation, no public safety threat was identified," Ottawa police said in a statement that afternoon, adding that two vehicles of interest and two persons of interest were located.

The sources said the vehicles were "cleared" and any potential threats they posed were unfounded.