Fire services in Norfolk faced more than 20 cases of arson last year, figures from the Home Office show.
In the 2017-18 financial year, the Norfolk Fire and Rescue Service attended 26 deliberately started house fires, 6pc of the 456 house fires in the area.
Since 2013, seven people have been killed in arson attacks.
The figures show that 24 people lost their lives in incidents attended by fire services over the last five years, two in the last year alone.
There were 85 casualties last year, including 44 people who were taken to hospital as a result of their injuries.
Dave Green, national officer at the Fire Brigades Union, said: 'Starting fires deliberately in the home is a heinous crime. Rightfully, it is a serious criminal offence punishable by law. Arsonists do not just put the immediate victims at risk; they put whole communities and firefighters themselves in jeopardy.'
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