Two more people in Shanghai have been confirmed to be infected with the deadly H7N9 bird flu, local authorities said Sunday.

One is a Shanghai resident and the other is from neighboring Anhui Province.

The two male patients, 67 and 59 years old, respectively, developed flu symptoms in late March and were diagnosed with pneumonia over the last week, the city's health and family planning commission said in a statement.

An initial investigation showed that six people who have had close contact with the two have not exhibited flu symptoms.

Shanghai had 10 confirmed H7N9 cases as of Sunday evening, with four resulting in death. The other six patients have been quarantined and are undergoing treatment.

Authorities have placed 194 people who had close contact with the 10 infected people under medical observation. Two have exhibited symptoms, although bird flu has been ruled out as the cause of their illness.

To prevent the spread of the virus, authorities have ordered the slaughter of 98,000 poultry and incinerated them, according to the municipal agriculture commission.