Vandals are being hunted by South Yorkshire Police after stones were thrown at cars from a viaduct.
Three motorists called the police after their cars were damaged on Herries Road, Shirecliffe, on Wednesday.
Police patrols have been stepped up.
A South Yorkshire Police spokeswoman said: "We received three reports between 5.15 and 5.20pm of youths throwing stones onto the road.
"Local officers will be patrolling in the area to gather any information about those who may have been involved, as well as offering some reassurance to the local community.
"No further incidents have been reported since Wednesday evening but these patrols will continue into the weekend."
Anyone with information should call South Yorkshire Police on 101.