St Joseph’s Roman Catholic Primary School, in Harlesden, was evacuated on Tuesday (September 22) after a fire broke out.
Around eight fire engines and 58 firefighters attended the blaze at the school, in Goodson Road, at 3pm.
London Fire Brigade (LFB) station manager Sean Madeley, who was at the scene, said: "540 pupils and 65 staff were safely evacuated from the school as soon as the fire alarm sounded and there were no injuries.
"Quick thinking firefighters laid down plastic sheeting in the lower floors to minimise water damage. Crews used aerial appliances to tackle the fire from above but this is likely to be a protected incident.”
The roof of the building was completely destroyed by fire and most of the second floor was also damaged in the blaze.
The fire was brought under control at 9pm, with the cause still unknown.
“Crews were at the scene throughout the evening and are likely to remain there this morning, cooling down remaining hot spots.”
In a statement, issued on Wednesday (September 23), a Brent Council spokesman said: “The school will be shut until further notice and all parents have been informed.
“There is also some traffic disruption on Goodson Road whilst the school buildings are made safe.
“The school has put in place its business continuity plan with the support of other local schools to ensure that pupils’ education is not affected. Parents will be informed as soon as these arrangements are finalised.
“We’re very grateful to LFB for their prompt action, and for working through the night.”