MONTREAL -- UPDATE: Montreal, Laval going back to 8 p.m. curfew while four other Quebec cities extend lockdown. Read the latest on this story here

Quebec's government, which usually saves its most urgent COVID-19 news for rare 5 p.m. press conferences, has scheduled a second one in a week, on Thursday, amid reports of a skyrocketing caseload in Quebec City.

The last-minute press conference was announced Wednesday evening, and the province has so far given no indication of what leaders will address.

Some French-language media outlets reported Wednesday night that public health officials in Quebec City are very alarmed as they prepare to announce what's reportedly the worst ever single-day increase of cases in that region.

An outbreak linked to a gym in the city, Mega-Fitness, has been spiralling in size for the last few days, with over 400 infections now linked back to the gym and one client dead.

The city's public health spokesman hasn't responded to a request for comment on the broader situation.

The decision to hold Thursday's press conference appears to have been made quickly. At 6:46 p.m. Wednesday, Premier François Legault's daily schedule preview was updated with no sign of the press conference. Just 90 minutes later, at 8:18, his schedule went out again with the 5:00 event included.

The press conference will be held in Montreal, which is a fairly unusual move for Premier François Legault, but it's less uncommon when the National Assembly is on a break, which is the case this week.

Quebec City is already in a 10-day lockdown with schools and non-essential businesses closed, announced in another 5 p.m. press conference last week.

The most recent 5 p.m. press conference, just this Tuesday, contained new measures for Montreal and other red zones. 

On Wednesday, the Outaouais region also saw its highest ever number of new COVID-19 cases.

Also on Wednesday, Ontario declared a new state of emergency and issued a 28-day stay-at-home order as caseloads there continue to grow quickly.

Just hours before Legault's event was announced, the Parti Québécois criticized the CAQ government for its high-profile press conferences, saying these are not supposed to be "a chance to show off."

The opposition party asked the government to begin releasing its new written rules in writing ahead of every verbal announcement in order to keep focus and help journalists do their jobs.

LISTEN ON CJAD 800 RADIO: Does the CAQ government have an unfair advantage with their press conferences? Political analyst Tom Mulcair weighs in

Does the CAQ government have an unfair advantage with their press conferences?