WESTBOROUGH, Mass. -- Police in Westborough are investigating a series of incidents involving rocks hitting passing cars on Route 9.

NewsCenter 5's Shiba Russell reported that drivers are being warned to be on the lookout for flying rocks near the Connector Road Bridge about 1 mile from Interstate 495.

They said drivers traveling eastbound on the road early in the morning have been hit by flying rocks or debris and several have been injured.

They said at least two drivers were hurt by rocks recently while they were traveling on the road between 4:30 and 5:30 a.m. At least seven vehicles have been damaged since July 11 and one driver was hospitalized after a piece of windshield glass flew into his eyes on Monday.

Another driver was treated for cuts to his hand after his windshield was broken.

Police are not sure whether the rocks were deliberately thrown from the bridges, but they asked that anyone noticing any suspicious activity give them a call.