Shots were fired at a council van as the driver sat inside having his lunch.
Five pellets believed to be from an air gun hit the Transit parked at playing fields in St John's Road, Utley, on Tuesday.
Police say it was only through luck that nobody was injured. Minor damage was caused to the van.
The incident came just days after vandals ripped tiles from the roof of a sports pavilion at the same site.
Sgt Allan Gee, of Keighley police, says: "The van driver heard a cracking noise but did not think too much about it. When he got out he spotted the damage to the vehicle.
"It is not clear where the shots were fired from or by whom.
"Anyone who uses a gun in such an irresponsible manner clearly has no regard at all for people's safety. Fortunately, in this instance, no one was hurt but this sort of behaviour has the potential to cause very serious injury.
"We are very keen to hear from anyone who may have witnessed this incident, which happened between 12.15-12.30pm, or has information which might help us apprehend the culprit."
Anyone able to help should contact Crimestoppers on 0800 555111.
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