http://www.who.int/csr/sarsarchive/2003_02_02b/en/

Here's an excerpt:

The SARS outbreak in Hong Kong SAR has developed an unusual pattern of transmission. This pattern is different from what is being seen in the vast majority of other SARS outbreaks, and is not yet fully understood. The number of cases is continuing to increase significantly, and there is evidence that the disease has spread beyond the initial focus in hospitals.

These developments raise questions related to other routes of transmission, in addition to well-documented face-to-face exposure to droplets released when an infected person coughs or sneezes. Epidemiologists are considering whether SARS is being transmitted in Hong Kong by some environmental means for which no satisfactory explanation has been found.

Particular concern centres on a large cluster of cases linked to residential buildings in the Amoy Garden housing estate in the Kowloon district of Hong Kong.