ITV News understands that there were people working on the roof of the National Library of Wales today, when the fire started.
Nobody is thought to have been injured.
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Updates on Swansea City, Cardiff, Wrexham and Newport County.
There will be some light rain but it's mostly dry with sunny spells developing.
The UK has experienced a 4.4 magnitude earthquake. The epicentre was Cwmllynfell near Pontardawe in the Swansea Valley.