Dramatic footage caught by eyewitnesses shows the scale of the fire and subsequent damage to the historic Aberfan chapel.
Fire crews responded to the incident at just before 2 this morning and have been re-inspecting the scene throughout the day.
Structural engineers have also visited the chapel, with Jennie Griffiths of South Wales Fire Service tweeting the structure was "in danger of collapse"
The chapel was used as a mortuary by the Aberfan community after the coal tip disaster of 1966, where mud and debris flooded Pantglas Junior School killing 116 children and 28 adults.
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A wet and windy night for much of Wales, with clear skies further inland.
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