China says it has sealed off a Severe Acute Respiratory Syndrome (SARS) research lab in Beijing after two lab workers were confirmed to have contracted SARS and the mother of one of the workers died ? apparently the first known SARS-related death this year.

Chinese health officials said Saturday that a nurse who looked after one of the SARS-infected lab workers is suspected to have caught SARS and is currently in isolation.

China's official Xinhua News Agency said the confirmed cases both had worked in laboratories in Beijing for China