HONG KONG - Hong Kong on Saturday declared a mystery virus outbreak as an "emergency" -- the city's highest warning tier -- as authorities ramped up measures aimed at reducing the risk of further infections spreading.

"Today I declare the lifting of the response level to emergency," chief executive Carrie Lam told reporters.

Lam held emergency meetings with health officials on Saturday morning after returning from Davos as criticism of her administration's response had risen in some quarters.

Of the 5 people who have tested positive for the virus in Hong Kong so far, 4 arrived via a newly built high-speed train terminal, which connects with the mainland.

That has led to calls from some to limit, or even halt, arrivals from the Chinese mainland, which remains the epicenter of the outbreak with 41 people dead so far.

• China virus death toll jumps to 41, cases soar to nearly 1,300

At a press conference on Saturday, Lam said all flights and trains from Wuhan would be canceled until further notice.

There were no restrictions on transport from other Chinese cities, but all mainland arrivals will now need to sign a health declaration form.

Schools and universities, which are currently on a Lunar New Year break, would remain closed until Feb. 17, she added.

A string of public events, including a new year gala and next month's marathon, would also be called off.

"We haven't seen serious and widespread infections (in Hong Kong), but we are taking this seriously and we hope to be ahead of the epidemic," Lam said.

Lam currently boasts record low approval ratings after 7 months of pro-democracy protests that have left the city ideologically torn apart and helped tip it into recession.

"We must stand united so that we can prevent and control the disease," she said, in a nod to the political unrest.