"It's too dangerous to go in at the minute, so we're carrying out fire investigation using other means talking to witnesses, interrogating systems that are functioning within the building, so the fire alarm, CCTV etc."
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The Met Office has issued a yellow weather warning for strong winds on Saturday which could cause damage, disruption and power cuts.
Following criticism from MPs and campaigners, the work and pensions secretary said the helpline would be free by the end of the year.
A report into a riot-hit jail has revealed inmates were locked up for as much as 23 hours a day.