Homes were evacuated and several people taken to hospital after a “chemical incident” in south-east London.
Emergency services were called to Alwold Crescent in Lee at 09:50 BST over fears residents were suffering reactions to an unknown chemical smell.
Eight people were taken to hospital or assessed by paramedics with reports some had suffered nausea and vomiting.
London Fire Brigade said a chemical response team was trying to establish the cause.
Scotland Yard said the incident was not believed to be crime-related.
Five fire engines, along with paramedics and police were all deployed to the area.
A spokeswoman for the brigade said 12 people were evacuated from houses “as a precaution”.