Tianjin confirmed on Friday that three cases of the novel coronavirus were reported among colleagues who are crew members in the same workshop at the city's high speed rail's passenger service section.

One went to Wuhan, the epicenter of the disease, for a business trip before falling ill, and was confirmed as the city's second case on Thursday.

Two of his colleagues were diagnosed as the fifth and sixth cases in the city on Friday.

Until Friday mid-afternoon, the North China city had confirmed seven cases of the viral pneumonia.

People who work with the three are under close observation and the whole workshop was closed to undergo strict disinfection.

On Friday the level was raised to the top response under the four-level major public health emergency response system. Since Thursday, the city has announced it would close all public museums, halt large festival celebrations and temple fairs in Dule Temple and Yangliuqing Ancient Town, as well as some major festival activities planned in major tourist destinations, including the Wudadao, -- the Five Avenues, one of the top tourist destinations in China during festivals.