Police are warning people in the Heanor area not to approach a discarded safe which contains bullets.
Sometime between 4pm on Thursday November 30 and 10am on Saturday December 3, offenders broke into a house on Nelson Street by smashign a window.
They stole a locked safe containing live rifle ammunition. The victim has a firearms licence.
Police are unsure if the thief managed to get into the safe but say attempts to get into it could cause the bullets to fire.
Witnesses, or anyone who discovers the safe, should call PC James Shaw on 101, quoting reference 17000524957, or send him a message online by visiting the Contact Us section of the website www.derbyshire.police.uk/Contact-Us.
You can also call Crimestoppers anonymously on 0800 555 111.