A section of Watford High Street has been closed after a chunk of masonry fell off a building.
Police officers witnessed the collapse shortly after 8.10am and cordoned off the street outside Que Pasa restaurant.
Firefighters arrived on scene to help install a safety line within ten minutes.
A structural engineer is en-route from the council to examine the damage.
Giles Cooper, spokesman for Hertfordshire Constabulary, said: "Officers had been in the area and witnessed some part of the building falling down on the High Street.
"They were concerned that there was a further chunk of masonry loose on the building.
"The officers closed the path and called the council structural engineer.
"The fire service was called to put a safety cord in place.
"The structural engineer is still on his way. The path remains closed at the moment."