Police are hunting two men after an attempted robbery at a garage in Long Sutton.
The men entered the BP garage in Wisbech Road at about 9.15pm on Wednesday and demanded money from the till.
One of the suspects was carrying a weapon that has been described as a firearm and the other a bag.
They were disturbed by customers entering the shop and they left empty-handed, crossing the road and going into the field opposite.
Police are appealing for any witnesses who may have seen the suspects, wearing dark clothing and balaclavas, leaving the area or who may have found discarded items of clothing in the vicinity.
Anyone with information should call 101 and quoting incident 392 of October 3.