PHILADELPHIA (AP) - Two people are unaccounted for after a sightseeing boat carrying 37 people was hit by a barge and overturned in the Delaware River in Philadelphia. The Coast Guard says there were 35 passengers and two crew members aboard the amphibious "duck boat." A spokesman says Coast Guard boats assisted by police and fire crews worked to rescue people from the water. Fire officials say three people were taken to hospitals. A security guard who was patrolling the waterfront says bystanders screamed as the barge hit the boat. He says after the collision, the duck boat began to turn over -- in what "almost looked like slow motion." He says he saw life vests popping up immediately, and then saw police boats pulling people out of the water. Television footage showed at least five people being pulled from the water wearing life vests in an area of the river near the Old City neighborhood.