POLICE are investigating a fire at the Co-op department store in Ilkeston as arson.
Fire crews found a window frame at the South Street store had been on fire but had been put out by staff when they arrived.
A police spokesman said they are checking CCTV to see if the fire, which started at about 10.40am on Sunday, started deliberately or whether it had been sparked by a discarded cigarette.
A spokesman for Midlands Co-operative Society said: “The fire caused smoke to enter via the window display, which set off the stores fire alarm system. Our colleagues ensured that the department store was evacuated quickly and the fire brigade were called.”
The store re-opened at 11.25am.