Health authorities in East China's Anhui province have confirmed three locally transmitted cases of COVID-19 and classified three areas as medium-risk for infection as of Friday morning.

One case was reported in Lu'an city on Thursday, while two more cases have been reported in Hefei, capital of the province, by Friday morning, according to local health commissions.

A woman surnamed Zhang who works in a photography studio in Lu'an tested positive for the coronavirus early on Thursday morning. Her infection was confirmed in the afternoon. She has not traveled outside of Anhui recently, according to the Lu'an health commission.

As the authorities tracked her close contacts, the second case, a woman surnamed Li, was confirmed on Thursday evening in Hefei's Feixi county.

The third case, a woman surnamed Lyu who is Li's colleague, was confirmed as being infected on Friday morning, according to the Hefei health commission in a news conference on Friday morning.

Li traveled by plane on May 1 from Dalian of northeastern China's Liaoning province to Hefei, and then arrived at Lu'an by bus for photography training in Zhang's studio.

Anhui authorities said in a statement that Li was suspected to have had contact with people in Dalian who returned from overseas, while Dalian's health commission denied this in a statement on Friday morning after an epidemiological survey.

Li returned from Lu'an to Hefei by train on May 8 and remained in Feixi county, mostly in a hotel, before she was found to be related to Zhang's case on Thursday.

Li's colleague arrived at Hefei by train on May 10. The two women had been staying in the same hotel room.

A shopping center and a residential community in Lu'an, in addition to a commercial building in Feixi county, have been classified as medium-risk areas for COVID-19 by Friday morning, according to the local health commissions.