Vandals set fire to an outside toilet behind a nursery in Heanor in the early hours of Sunday morning.
Crews from Ilkeston and Heanor were called to Cottage Day Nursery on Mansfield Road at around 5am after smoke was seen coming from behind the nursery, after a neighbour on Mansfield Road had raised the alarm.
Two firefighters had to use breathing apparatus as they put out the flames.
Manager Bridget Pilgrim said this week: “A lot parents were very worried when they heard on the radio that the toy shed was on fire, but there’s been no damage to the nursery or equipment.
“It’s one single toilet that’s no longer usable.
“We were very lucky because people raised the alarm very quickly.
“This is the first time we have had any trouble with vandals.”
The Cottage Day nursery was open as usual on Monday.
Police were informed about the incident as the fire was believed to have been started maliciously.
A joint investigation between police and the fire service is now under way.
Anyone with information about the fire is asked to call police on 101 or Crimestoppers anonymously on 0800 555 111.