A man has been taken to hospital after a huge fire broke out at the mosque in southwest London on Saturday.
The fire, which is believed to have been caused by an electrical fault, started at the Baitul Futuh Mosque in London Road, Morden.
It sent plumes of smoke into the air which were so thick they could be seen more than 10 miles away, ITV television network reported.
More than 80 firefighters attended the scene to put the fire out hours later.
Eyewitness Mark Gale, 40, said: "It's just solid smoke, it's so thick you can hardly see the firefighters through it. There must be about a hundred emergency vehicles down there."
The London Ambulance Service said they treated a man in his 40s for smoke inhalation. He was taken to hospital but has since been released.
A large number of people have had to be evacuated and that the ground and first floors have been affected by the fire.
London Road was closed north and southbound from Crown Road to Central Road. Bus routes 80, 90 and 154 were also being diverted.