STAMFORD - State police are trying to determine what caused a 13-car pileup on I-95 in Greenwich Sunday.The accident happened on the northbound side of the highway between exits 4 and 5. According to police, a loose construction barrel ended up in the middle of the highway, causing the cars to collide. The pileup caused I-95 to be shut down for more than two hours.The driver of the lead car in the pileup told News 12 Connecticut that the overpass created a dark shadow and that by the time he saw the barrel, it was too late. He says he had to slam on the brakes to avoid hitting it.Two people were taken to Stamford Hospital with minor injuries from the pileup.Stamford's Camp Auto Body says there were eight cars involved in the pileup that are now at the shop. The auto shop says all of the cars have significant damage to both their front and rear. I-95 in Greenwich reopened after accident