Two 13-year-old boys have been arrested after the Winnipeg Police Service says they were throwing rocks at cars from an overpass.

According to police, at around 10:15pm on June 17, 2014, three youths were throwing rocks off an overpass at Pembina Highway and Bishop Grandin Boulevard.

Four east-bound vehicles travelling around 80km/h were struck, causing $2,500 worth of damage.

Drivers of three vehicles pulled over to pursue the alleged rock-throwers.

Police say a 22-year-old man caught up with one youth and was assaulted.

Police say they arrested two suspects and while one youth was in police custody, an officer was assaulted.

His injuries to the upper-body were minor.

Two 13-year-old boys are facing charges and have been released on a Promise to Appear.

Police say the investigation is continuing as a third youth has yet to be arrested.