Ontario's health ministry is reporting 211 new cases of COVID-19, bringing the provincial total to 1,355.

The total includes four new deaths in Ontario — two reported Sunday morning and two more in the afternoon. That means 23 people have died of the virus in the province. This morning the ministry said two of the deaths have had not been confirmed by a lab.

It's the largest single-day increase in cases so far.

A total of 7,203 cases are under investigation, while 40,630 people have tested negative for the virus.

On Sunday, officials announced that at least eight firefighters have tested positive for COVID-19. The number includes six in Toronto, one in Mississauga and one in Oakville. It was not immediately clear if the eight are included in the case numbers reported early Sunday.

Meanwhile, a First Nation in southern Ontario said it was erecting checkpoints at entrances and exits to its territory after confirming their first cases of COVID-19.

The Six Nations of The Grand River said Sunday that two people on the reserve had tested positive and were self-isolating.

Elected Chief Mark Hill said the move to set up checkpoints represented a drastic step in their fight against COVID-19.

The overall case numbers, released Sunday morning, come after the Ontario government issued an emergency order Saturday night prohibiting gatherings of more than five people. It replaces a previous ban on public events of more than 50 people.

Ontario Premier Doug Ford said the order, issued under the Emergency Management and Civil Protection Act, is in an attempt to stop the spread of the virus. The order applies to organized public events and social gatherings, the province says.

Ford said in a news release that "stronger action" is required to flatten the curve of cases.

5-person limit designed to ensure physical distancing

"If we are going to stop the spread of COVID-19 now and keep our communities safe, we need to take extraordinary measures to ensure physical distancing," said Premier Doug Ford.

"I strongly encourage everyone to do the responsible thing and stay home unless absolutely necessary. I can assure everyone that we will do everything in our power to stop this virus in its tracks."

Ford noted at a news conference on Saturday that there are exceptions to the new emergency order severely limiting the size of gatherings.

The order doesn't apply to private households with more than five people. Child-care centres that look after the children of front-line workers are limited to 50 people. And up to 10 people are allowed to gather at funerals.

Ontario Premier Doug Ford holds a news conference with Health Minister Christine Elliott and Finance Minister Rod Phillips at Queen's Park in Toronto. (Frank Gunn/Canadian Press)

According to the province, public events and social gatherings include parades, weddings and communal services within places of worship.

Failure to comply with an order made during a declared emergency can result in a daily fine of $750, under the Emergency Management and Civil Protection Act.

And if a person obstructs another person exercising a power, or performing a duty, in keeping with an order made during a declared emergency, the offender could face a daily $1,000 fine.

Police can also issue fines under Part I of the Provincial Offences Act or issue summons under Part III.

"We have confidence that Ontarians will follow the medical advice and follow the emergency orders issued," Greg Flood, spokesperson for the Ontario Solicitor General's ministry said in an email on Sunday.

Shoppers in Toronto stock up in reaction to the COVID-19 pandemic. Ontario Premier Doug Ford Ford has announced stiff new measures to prevent price gouging amid the outbreak. (Evan Mitsui/CBC)

Ford has also announced stiff new measures to prevent price gouging for important products during the COVID-19 crisis.

He said individuals found guilty of price gouging could face fines of $100,000, while company directors could face fines of $500,000 as well as a year in jail.

Ford said corporations may be fined as much as $10 million. The new rules went into effect on Saturday.

Province issues new instructions for construction sites

As for the construction industry, the Ontario government announced on Sunday an update to a "guidance" document for employers to help prevent the spread of COVID-19 on construction sites.

The update instructs employers to do the following:

Provide better on-site sanitation, including a focus on high-touch areas like site trailers, door handles and hoists.

Communicate roles, responsibilities, and health and safety policies, by posting site sanitization schedules and work schedules.

Enable greater distances between workers by staggering shifts, restricting site numbers and limiting use of elevators.

Protect public health by tracking and monitoring workers.

"Keeping job sites open during the current pandemic requires a heightened focus on health and safety," Ontario Labour Minister Monte McNaughton said in a news release. "We all have a role to play in preventing the spread of COVID-19."

Construction workers erect safety fencing on a condo project in downtown Toronto. The Ontario government announced on Sunday an update to a 'guidance' document for employers to help prevent the spread of COVID-19 on construction sites. (Frank Gunn/Canadian Press)

Also on Sunday, Prime Minister Justin Trudeau announced new federal funding for those experiencing higher levels of stress because of self-isolation policies — including children, seniors, the homeless and those facing violence at home.

He said the government is contributing $7.5 million to Kids Help Phone to hire more counsellors, adding that children feeling anxious should go online, call 1-800-668-6868, or text 686868 to reach the service.

Peel region first responders salute health care workers

Meanwhile, in Peel region, police, paramedics and firefighters drove by Trillium Health Partners in Mississauga on Saturday in a parade, with sirens on and lights flashing, to show their support for health-care workers.

"You are truly our superheroes and we WILL beat #COVID-19!" Peel police said in a tweet.