Two schools and nearby homes have been evacuated after a suspected Second World War bomb was discovered on a building site.
A huge cordon is in place and roads have been closed after the unexploded device was found near Brondesbury Park in Brent, north-west London.
The army has been called in to deal with the bomb while police and the fire service also remain on the scene, Brent Council said.
Police said they were called to The Avenue, near the junction of Willesden Lane, at around 11.30am on Thursday following the discovery.
Superintendent Nigel Quantrell said: "I would like to thank the community for their continued support as we and our partners deal with this incident.
"I can assure you that we are working very hard resolve the situation. The public's understanding and cooperation is deeply appreciated."
Malorees Junior School and Marylebone Boys' School had been evacuated and a 200 metre cordon is in place at the scene, Brent Council said.
A rest centre has been set up at St Martin's Church on Mortimer Road, Kensal Green, for residents affected by the disruption.
The army is working to make the bomb safe but the operation is likely to last until at least Friday afternoon, the council said.
More than 50 people who have been evacuated from their homes are currently at the rest centre, where several British Red Cross volunteers are on hand to provide support.