Detective Sergeant David Speight says whoever caused the fires may have flash burns on their body.
Michael and Angela Broderick, who are both deaf, had a narrow escape when an arsonist destroyed their home in Burbage in Leicestershire.
Police are appealing for the public to contact them if they have any information.
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England and Notts County Ladies goalkeeper Carly Telford will launch a campaign later today to encourage women to get involved with sport.
Isolated showers will largely die away, and winds will decrease. Feeling chilly with clear spells.
Any early showers will die away leaving most of the evening and night dry with clear spells.