June 14, 2017 3:14 AM EDT

Londoners watched in shock as a 24-floor residential tower was transformed into an urban inferno early Wednesday.

Flames engulfed the Grenfell Tower, in west London’s North Kensington neighborhood, starting at around 1 a.m. local time, and the high-rise apartment complex continued to burn for more than four hours.

The Associated Press reports that 45 fire engines and more than 200 firefighters rushed to the scene to respond. At least 50 people were taken to hospitals, according to the London Ambulance Service, amid fears that others may have been trapped inside.

The city’s Mayor Sadiq Khan said on Twitter that the blaze is being treated as a “major incident.” Emergency responders are still on the scene.

London Fire Brigade Commissioner Dany Cotton confirmed at a televised press conference that there were a number of fatalities, but the death toll is still unclear. The cause of the fire is still unknown.

This is a developing story, please check back for updates.

 

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