HONG KONG (AP) — Hong Kong authorities on Friday suspended several government officials from duty and will order about 170 people to be quarantined at a government facility after they attended a birthday party where two guests later tested positive for the coronavirus.

Hong Kong leader Carrie Lam said in a statement late Friday that the officials who were at the party and who are subject to quarantine would be suspended from their duties and must use their vacation days while they are isolated for 21 days.

Fears of a new virus cluster were sparked when a second guest at the Jan. 3 party preliminarily tested positive. On Friday, health authorities said all party guests would be classified as close contacts and be sent to mandatory quarantine if the second guest was confirmed as a positive case.

The city has been racing to control the omicron variant, with authorities locking down multiple residential buildings for mass testing and sending hundreds of people into quarantine.

About 170 guests attended the birthday party, including about a dozen government officials and nearly 20 lawmakers. Officials in quarantine include police chief Raymond Siu and Secretary for Home Affairs Caspar Tsui, among others.

“We now think that every person who had gone to the party is now a close contact. Therefore, our quarantine work is specifically aimed at the people who have attended the party,” said Chuang Shuk-kwan, head of the communicable disease branch at the Center for Health Protection during a news conference Friday.

Lam said an investigation will also be conducted to assess whether the officials breached conduct by attending the event.

“I have to reiterate that concerted efforts of the whole society are needed to fight the virus and that Government officials should lead by example, abide by the rules, stay vigilant and refrain from taking part in high-risk activities,” Lam said, adding that she would take “appropriate actions” against the relevant officials following the investigation.

Local media including the South China Morning Post reported that the party was held for Witman Hung, the principal liaison officer for Hong Kong at the Shenzhen Qianhai Authority, which oversees economic development between Hong Kong and the Greater Bay Area.

Director of Immigration Au Ka-wang, who was at the party, apologized in a statement Friday, saying he would be more vigilant in the future.

“Regarding the additional burden to the epidemic prevention work and the disturbance to the public as a result of my personal behavior, I offer my sincere apology to all people of Hong Kong,” he said.

Hong Kong tightened anti-virus measures this week, banning dining-in at restaurants and eateries after 6 p.m. and ordering businesses such as museums, beauty salons and gyms to close for two weeks. The city has also banned passenger flights from eight countries, including the U.S. and Britain, from landing until at least Jan. 21.

Authorities reported 33 new confirmed infections on Friday, 26 of which were imported. They also reported over 30 preliminary positive cases awaiting official confirmation.

The city has reported a total of 12,749 infections and 213 deaths since the pandemic began.