By David Young-
The Metropolitan Police is expected to give an update on damage that might have been caused to evidence store relating to ongoing criminal cases.
London Mayor Sadiq Khan said he was in close contact with the fire commissioner.
The force said some essential police property was moved to a place of safety.
The roof of Forest Gate police station was “completely destroyed” but that no injuries had been reported.
Police said the incident was not initially being treated as suspicious.
They added that policing operations in the area would be able to continue as normal.
The fire is believed to have broken out on the third floor, police said.
Photos from the scene showed large amounts of smoke billowing from the length of the building’s roof.
Firefighters from Stratford, Leytonstone, Plaistow and other nearby stations were sent to help local crews.
Four long turntable ladders were deployed to help tackle the fire from above, while drones were used to give firefighters a better view of the blaze.
Superintendent Dan Card, speaking outside the smoking red brick police station, said: “The fire has now been contained and the cause of the fire is not being treated as suspicious at this stage.
“I’d like to reassure the residents of Newham that our policing response in the area has not been affected and we are able to continue to do our job of keeping the people of Newham and London safe.”
London Fire Brigade (LFB) is now investigating the fire, and says its probe may be lengthy “due to the scale and nature of the incident”.
The roof of the police station, which is where the fire was located, “was completely destroyed”, said LFB.
The brigade was called to the scene shortly after 4.15pm, and had the fire under control by around 11.10pm.
The fire brigade said the fire had been prevented from spreading to adjacent buildings.
Residents in the area have been told to keep windows and doors closed.
In a video posted to social media, Superintendent Dan Card said: “The fire has now been contained and the cause of the fire is not being treated as suspicious at this stage.
“I’d like to reassure the residents of Newham that our policing response in the area has not been affected and we are able to continue to do our job of keeping the people of Newham and London safe.”
Residents in the area were earlier told to keep their doors and windows shut and avoid the area due to the amount of smoke.