Two people and a toddler escaped a house fire which police believe was started by cannabis-growing equipment.
Emergency services were called to the home in Falkland Road, east Hull, just before 4am.
A man, 32, a woman, 26, and a 16-month-old girl were in the house when the fire started but escaped unhurt.
Investigations suggested the fire started because of an electrical fault caused by equipment used in a cannabis factory.
A 32-year-old man has been arrested and is in police custody.
A Humberside Police spokesman warned people of the dangers of growing cannabis in residential properties.
He said: "We would warn those setting up cultivation equipment that, not only could this lead to criminal investigation, but also risk the lives of occupants and neighbouring properties.
"Often the buildings themselves are tampered with, resulting in damage to the walls, floors and ceilings (and) the electrics.
"We would also urge landlords to thoroughly check who they are leasing their houses to before handing over the keys."
