A handgun has been discovered by workmen in Derby, prompting a police investigation.
Officers were called to Tintagel Close, in Normanton, at 1130 GMT on Wednesday after workmen found a bag they believed contained a gun.
The area was cordoned off to allow for a police investigation by specialist officers.
A spokesperson for Derbyshire Police sad firearms experts were due to examine the weapon.
House-to-house inquiries are being carried out, police said.
Ch Insp Sunita Gamblin, of Derbyshire Police, said: "We have acted immediately to try to trace the origins of this weapon.
"We would like to hear from anyone who knows how the gun came to be hidden here."
She said anyone who had information about this or any gun crime should call the Operation Redshank Hotline or Crimestoppers.
"I also want to issue a reminder that if you carry anyone's illegal gun you are liable for a five-year minimum prison sentence."