Paramedics treated a man for smoke inhalation after a fire at Kingston Mosque.
Flames broke out at the Kingston Muslim Association building shortly before 6pm yesterday.
About 100 children were among those who were evacuated from the building before firefighters arrived.
London Fire Brigade said a staircase and five per cent of the building's roof were damaged by the fire, but that no injuries were reported.
The Metropolitan Police said the fire was not being treated as suspicious.