The Ottawa Police Service says criminal investigations are underway in connection with incidents during Saturday's "Freedom Convoy" protest on Parliament Hill and throughout the city's downtown core.

"Several criminal investigations are underway in relation to the desecration of the National War Memorial/Terry Fox statue, threatening/illegal/intimidating behaviour to police/city workers and other individuals and damage to a city vehicle," police said in a tweet Sunday.

Thousands of protesters descended on Ottawa's downtown core on Saturday, creating massive gridlock. The bulk of the crowd remained on Parliament Hill but there were many more people wandering through the streets, in some cases engaging in behaviour that has been condemned by officials, including standing on the Tomb of the Unknown Soldier at the National War Memorial and attaching an upside down Canadian flag to the Terry Fox statue on Wellington Street. The Shepherds of Good Hope also said some protesters harassed staff and volunteers at their soup kitchen on Saturday.

Police said no arrests were made Saturday.

"Officers encountered several challenges with demonstrators, including sporadic road blockages by trucks, which officers worked to clear," a press release said. "These high-risk situations were de-escalated and resolved with no arrests."

The press release did not mention the criminal investigations.

In a statement to CTV News, the Ottawa Police Service confirmed that the incident at the Tomb of the Unknown Soldier was under investigation. Police also confirmed to CTV News that they are working with organizers of the protest on a route and safe manner to clear the downtown.

Speaking on Newstalk 580 CFRA on Sunday, Ottawa police spokesperson Const. Amy Gagnon urged residents who witness crimes to call police directly.

"I know there's a lot circulating on social media and we want to remind people that we actually can't police based on social media," she said. "We actually haven't had incidents reported, so we're asking people to call us. Please call Ottawa police if there's an incident to report."

Gagnon said there are officers prepared to investigate any criminal reports and they are ready to lay charges if necessary.

"We are here to help the residents and so if you have experienced or are experiencing threats or it does escalate to violence, please call us. We need to know so we can respond."

The protest against COVID-19 mandates and public health measures began as a convoy of truckers driving from B.C. to Ottawa, with many people coming along in personal vehicles. Protesters throughout the downtown core blared horns for most of the day Saturday and set off fireworks at night. Honking resumed downtown at around 8 a.m. Sunday as a smaller crowd began gathering on Parliament Hill.

Gagnon could not provide a specific estimate of the crowd's size but said it was in the thousands. She said police are preparing for the same number of people in the core on Sunday.

Barricades at War Memorial

Police also announced that barricades had been placed around the National War Memorial on Sunday to prohibit vehicles from parking at the cenotaph.

Barricade at war memorial

Police removed some cars that had parked around the monument Saturday morning. Later in the day, a video shared on social media showing a person standing on the Tomb of the Unknown Soldier shouting "freedom!" drew widespread condemnation from the country's top soldier, Chief of Defence Staff Gen. Wayne Eyre, Defence Minister Anita Anand, and groups like the Royal Canadian Legion.

Concrete barriers were placed on the paths leading up to the monument Sunday.

"We need our memorials to be respected. That behaviour is unacceptable and so we're putting up physical barriers to make sure that vehicles can't access the path and you will see an increased police presence around those areas as well," she said.

Gagnon also said police were also working to put barriers around the Terry Fox statute on Wellington Street.