Norfolk Police search sparked by student's toy machete
A helicopter, armed officers and police dogs responding to reports of a man with a sword were stood down after the weapon was found to be a toy machete.
Officers were "swiftly deployed" to the Mousehold Heath area of Norwich at about 17:50 GMT on Wednesday, police said.
But the search was called off when a mother told police her son was using a fake weapon in a film for college.
Norfolk Police said an 18-year-old man was given "strong words of advice".
The force said it responded quickly after two similar reports of a man carrying a weapon were received.
A member of the public phoned the control room when she realised her son's filming activity for a college project had triggered the response.
Officers were stood down once this had been confirmed, a spokesman said.
Supt Stuart Gunn asked anybody planning any sort of activity in a public place "that may prompt concern" to contact the force in advance.
"Imitation weapons should not be used, or left, in public view," he said.
"Public safety will always be our priority when dealing with such incidents."