North West London Jewish Day School was closed today after an unexploded wartime bomb was discovered by construction workers on a nearby building site in The Avenue, Brondesbury Park.

Hundreds of pupils were sent home and residents evacuated, as the police erected a cordon around the site, so that Army bomb disposal experts could assess the situation.

A picture taken by an Army photographer shows soldiers inspecting the device, weighing 500b (227kg), which was discovered buried deep at the site. Police said the disposal operation was likely to continue overnight.

Local councillor Carol Shaw, said: “The construction firm have been told that it might not be clear for three days.

“The police said a specific part coming from Gloucestershire may be needed to safely detonate the bomb. It’s very major and it could be very dangerous, which is worrying.”

Two fire engines and 14 firefighters were also dispatched to the site, after emergency services were called yesterday.

Nigel Quantrell, superintendent of Brent borough, said: "I would like to thank the community for their continued support as we and our partners deal with this incident.”

A property developer is building 74 apartments on the site.

Meanwhile, Brondesbury Park Synagogue opened its doors early on Friday to provide lunch and prepare Shabbat dinner for members of the community affected by the evacuation, writes Lee Harpin.

A message from Brondesbury Park's shul executive confirmed: "Over the last few hours, the police have expanded the scale of the evacuation zone which now covers a considerable swathe of the local area and affects a number of our members.

"The shul has opened its doors and will be providing such this afternoon and Shabbat dinner this evening to those members of the community who have been evacuated from their homes."

Members without alternative accommodation were also advised to contact the shul.

Elderly residents at a nearby jLiving (Jewish Community Housing Association) property were forced to leave their homes as 63 sheltered-accommodation flats were evacuated on Friday afternoon.

The pensioners were said to be in good heart. A jLiving spokesperson said: "The spirit of the blitz is kicking in".