Vietnam’s Prime Minister Nguyen Xuan Phuc ordered the country’s aviation authority to halt international commercial flights after the nation reported its first local coronavirus cases in almost three months, according to a posting on the government’s website.

The premier, who said “rescue” flights bringing Vietnamese home from abroad should continue, instructed the Ho Chi Minh City government to quickly trace and isolate everyone who came in contact with those who tested positive this week, the website reported.

The local government has isolated 513 people after three patients tested positive for the virus, according to a separate government website posting. A one-year-old boy and a 28-year-old female student were infected after coming in contact with a male teacher who tested positive. The male teacher earlier had close contact with another virus patient who left a quarantine area.

Phuc directed provincial governments to enforce social distancing “in high risk areas” in a reasonable manner so as not to hurt businesses and production activities, according to the posting.

Vietnam had 1,351 Covid-19 infections and 35 deaths as of Dec. 1, according to the health ministry.