At a press conference Wednesday, Premier François Legault confirmed 1,339 cases in the province - more than double Monday's number.
"In these three residences, all the necessary measures have been taken", said Legault.
Legault added the level of hospitalizations in Quebec remains low as do the number of patients in intensive care.
The Legault government's measure means that only essential services - such as grocery stores, pharmacies, banks and police departments - will remain physically open over the next three weeks.
Quebec leads the country in confirmed cases, but the premier and public health director Horacio Arruda said they fully expected to see the higher numbers because testing here is now in full swing.
The number of cases in the province rose to 1,339 on Wednesday, up 326 from the day before.
It's hard to determine the exact reason for all cases, said Drouin, who explained that in almost half of the cases, people were returning from a trip, but others may have had contact with travellers, and are even second or third generation transmissions.
The company said that it would continue to run its warehouses, distribution centres, and stores with street access during this time. "It's because there are situations where people who don't know they're sick, but are sick, can contaminate others".
There remained four deaths in the province linked to COVID-19 as of Tuesday afternoon.
However, he stressed that Quebecers of all ages are to consider themselves essentially locked down. "We are not in the step where we have to start giving fines but we have the power to do so", he said. In Quebec and Ontario, only essential business services are now allowed to stay open. It includes teachers working online, infrastructure maintenance, sanitation, manufacturers of food and medical supplies, hotels, movers, restaurants offering takeout only, banking and public transportation.
The province's liquor and cannabis stores will also remain open during that period, but clients are encouraged to place online orders.
She said that while the majority of cases involve travellers or their close contacts, the city is also seeing cases of community transmission. One person who had contracted COVID-19 has since recovered. Some may have few, if any symptoms, or may not know they're infected because symptoms of the novel coronavirus are similar to a cold or flu.
However, for some, including Canadians aged 65 and over, those with compromised immune systems and those with pre-existing conditions, the illness can be much more severe.