Police were contacted after tiles were thrown from rooftops in Dunstable on Monday.
A call was made to Beds Fire and Rescue Service shortly after 5.30pm after tiles had fallen from the roof above Halifax bank on High Street North.
A section of High Street North between Halifax and the traffic lights was closed while the roof was examined.
While the crew attended, a second call was received as youngsters were seen climbing scaffolding above 67 High Street North – some 150 yards away – throwing tiles into the street.
A Dunstable Gazette reporter avoided two missiles.
Beds Police also arrived following the reports of missiles being thrown.
The street was reopened by 8pm.
On Tuesday evening, Beds Fire and Rescue Services returned to High Street North to examine the roof above Halifax bank. A spokesman said: “We used the Luton Aerial Platform to assess the roof and there was no sign of loose tiles.
“We have concluded the tiles came from an unknown source and have passed the information onto the police to investigate.”