Two people were taken to hospital after a house was set on fire in Corby on Sunday.
Northamptonshire Police are appealing for information following a spate of arson attacks in the town since Thursday.
The first took place at about 11.30pm on Thursday in Lingfield Walk, when a wheelie bin and a pile of rubbish was set alight outside a house. Nobody was hurt in this incident.
The second fire happened at about 2.30am on Saturday at Bizzy Bees Minibus Hire in St James Road, when a temporary office building was broken into and set alight. Nobody was injured but the office building was destroyed.
The third fire happened at about 2.30am yesterday (Sunday) in Llewellyn Walk, where some rubbish outside a house was set on fire. The fire damaged both the inside and outside of the property.
The four people inside the house managed to escape, but one, along with a neighbour who went to help, had to be taken to Kettering General Hospital for treatment after inhaling smoke.
Officers investigating the three fires do not believe they are linked at this stage, but they have urged anyone with any information to call 101 or Crimestoppers anonymously on 0800 555111.