SHENZHEN -- A resident of Shenzhen City in south China's Guangdong Province has contracted the H7N9 strain of avian flu, local authorities said on Tuesday.

The city's health and family planning commission confirmed that Yang, 35, was suffering from H7N9 on Monday.

Yang is in a local hospital and her condition has been described as critical.

As Yang works as a maid, 28 people who had close contact with her have also been admitted to hospital for observation.

This is the first case of a human contracting H7N9 in Shenzhen this winter.

Previously, Shanghai Municipality, eastern Fujian Province and other cities in Guangdong have all reported cases of humans with H7N9.