Police are appealing for information after thousands of pounds' worth of damage was caused in a fire at a well-known furniture and toy shope in Ilkeston.
Officers believe a fire was deliberately started in Thorpes of Ilkeston in South Street at around 3.10am yesterday.
Derbyshire Fire and Rescue Service was alerted to the blaze at around 4.30am by a passer-by who could smell smoke.
Detective Constable Claire Croll, of Derbyshire Constabulary, said: "We would like to talk to anyone who has any information about this incident.
"There is quite considerable damage inside the shop, not only from the flames but also as a result of the smoke damage.
"As well as the damage there was the potential for harm to others, not least the fire officers who went to tackle the fire.
"We would particularly like to speak to, or receive information about, three young men dressed in black who were seen to approach the building at around 3.10am and were then seen running away five minutes later."
Anyone with information should call 101 and quote reference number 18*359138 along with the name of the officer dealing with the case, Det Con Claire Croll.