The Calgary Emergency Management Agency says international travellers are now being ordered to self-isolate when they arrive in the city, in order to prevent the spread of COVID-19.

"This is not a suggestion, this is not a guideline, this is an order," Calgary Mayor Naheed Nenshi said Tuesday, during an update to media at the city's emergency operations centre.

The order states that any individual who has travelled internationally must take all reasonable steps to isolate themselves for 14 days, with reasonable exceptions like visits to pharmacies if necessary.

In a daily update Tuesday afternoon, the province's chief medical officer of health announced that 23 more people in Alberta have been diagnosed with COVID-19, bringing the provincial total to 97. There are now 70 cases in the Calgary zone.

Five people in the province have been hospitalized, including two who are currently in intensive care units. The other 92 cases are all people who are self-isolating at home and are expected to make full recoveries.

WATCH | The City of Calgary provides an update on its COVID-19 response:

The Calgary Emergency Management Agency says international travellers are now being ordered to self-isolate when they arrive in the city, in order to prevent the spread of COVID-19. 31:56

Nenshi said it's not known why Calgary's number of cases is so high, but that it's likely tied to the city having an international airport. He said those arriving at the airport will be advised of the new order to self-isolate.

Officials from Calgary police, the fire department and Calgary Transit provided updates, reassuring Calgarians that they have personal protective equipment available to staff and that they are prepared for this emergency.

Transit fleet manager Russell Davies said one Calgary Transit worker, a training officer, has been diagnosed with COVID-19. Twenty-seven people who were in touch with that employee have been asked to self-isolate.

Davies said riders on airport buses will be instructed to enter buses from the back door, not the front, and reminded passengers that it takes a team effort to keep buses and CTrains safe.

"The bus is only as clean as it is when it leaves the facility. Once people get on board … then that's a different situation," he said.

The city is currently under a state of local emergency, and a number of facilities like recreation centres and library branches were ordered closed beginning Monday until further notice. On Tuesday, community centres were added to that list.

Earlier Tuesday, Alberta Premier Jason Kenney declared a state of public health emergency, saying seating in restaurants and coffee shops would be limited to a maximum of 50 people or 50-per-cent capacity, whichever is lower.

Takeout, delivery and drive-through service are permitted. Bars that don't allow minors, nightclubs and casinos were to close immediately. Bars that serve food and allow minors can continue to operate under the new guidelines.

Nenshi said that while the situation is serious, Calgary is well-prepared to handle it.

"It's been more than a century since we've seen a worldwide pandemic on this scale. Millions died from the Spanish flu. That is not going to happen here, that is not going to happen now," he said.

"I want to chart a course where people are going to say you overreacted, because that means we flattened the curve."

He thanked those working in grocery stores and pharmacies, saying they provide an essential service. And to make their jobs easier, he reminded Calgarians not to stockpile and to stay home as much as possible.

"The supply chains are solid, the shelves are getting restocked, we're going to be fine," he said.

Mass gatherings are now limited to no more than 50 attendees. This includes worship gatherings and family events such as weddings, the province said in a news release. Kenney said funerals with more than 50 people should also be cancelled.