Twelve potentially dangerous, explosive fog signals have been stolen from a vehicle in Stapleford.
Police were called following the theft from a contractor's vehicle on Birley Street between 3pm on Thursday and 6am the following day.
The fog signals were taken during the theft and detectives investigating their disappearance are appealing for anyone who sees them to get in touch.
The items are low-level explosives which are widely used in the rail industry.
They are designed to ensure the safety of contractors by giving an audible warning to train drivers as trains pass over the signals.
The signals were stored in a black-coloured bag which was left in the vehicle overnight and was taken during the theft.
Detective Inspector Ed Cook, from Nottinghamshire Police, said: "These fog signals are specialist equipment that are of no use or value to those who have stolen them - so it's possible that they will have been discarded following the theft.
"In the wrong hands, these signals can be dangerous to anyone who isn't professionally trained in their use and we are very keen to prevent anyone from coming to harm.
"If you know who has them, you have been offered them for sale yourself or you want to anonymously let us know where we can find these items, please get in touch."
Anyone with any information about their whereabouts is asked to call Nottinghamshire Police on 101, quoting incident number 107 of 10 March.