Firefighters have been called to a blaze at an electricity substation at New City Primary School.
Dramatic images of the fire began circulating on social media last night as crews from Plaistow, Stratford, East Ham and Poplar fire stations fought the flames.
More then 20 firefighters in four fire engines were at the scene after they were called at around 10pm.
The blaze was under control around three hours later.
The Tunmarsh Lane, Plaistow school itself is mostly unaffected, with only a small amount of brickwork being damaged.
The cause of the incident is under investigation.
Boleyn Trust run the school and Steven Lock, the chief operating officer, said staff have been to inspect the site.
"We will cooperate as much as we can with any of the services that need help at the site," he added.
The incident won't be affecting teaching, as the school broke up for summer holidays on Thursday, July 18.
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