Hope of finding two Hungarian passengers was fading the day after a Ride the Ducks tour boat capsized and sunk in the Delaware River.
"Close your eyes. That's what we can see. Nothing," said diver Lt. Andrew Napoli. The water is too murky and the currents are too strong for divers to go back down to the site where they found the Duck boat last night resting upright on the bottom on the river.
"There could be bodies inside. We're not sure. If it went down with bodies inside, those bodies could very well have been washed out of the vessel," said Napoli.
Rescue crews will continue to search by boat.
On Thursday, Ride the Ducks suspended duck boat operations nationwide. The Georgia-based company operates tours in San Francisco, Seattle, Atlanta, Newport, Ky., and Branson, Mo.
Most of the 37 passengers and crew jumped into the warm, dingy water Wednesday afternoon when the tour boat -- which was stalled in the water after an engine fire -- collided with a barge around 2:40, according to Philadelphia Police Deputy Commissioner William Blackburn. Emergency crews and citizens went into rescue mode immediately.
"The immediate response was first of all amazing and overall fantastic with the number of people who came out," said U.S. Coast Guard Capt. Todd Gatlin.
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Several visiting Navy SEALs were credited with being the first to jump into action. The SEALs were on their way to an event promoting a new program called Navy Seal Grove when they heard about the accident and rushed to the scene.
"We had a Philadelphia police officer actually jump in the water -- he was in full gear -- to stay with people until they could be rescued," said Blackburn.
People who saw what was going on from Penn's Landing near the Independence Seaport Museum, rushed over to help pull passengers ashore.
All but two of the passengers and crew made their way to shore. Eleven were taken to local hospitals and two were admitted – one for a broken jaw and the other for shock. Although many people did have life vests on, wearing them on a Duck boat ride is not mandatory.
"It is not required for them to have life vests. It is required for them to have easy access to life vests," said Capt. Gatlin.
The two missing tourists -- a 16-year-old girl and 20-year-old man -- were part of a large group of Hungarian tourists, sources told NBC Philadelphia.
The Hungarians were visiting the area as part of a missionary exchange program operating out of the Marshallton United Methodist Church in West Chester, Pa.
The National Transportation and Safety Board was on site to take over the investigation.
"We want to collect the perishable evidence; that information that can go away with the passage of time," said NTSB Board Member Robert Sumwalt.
Interviewing victims and gathering evidence usually takes up to a week. Determining the official cause of the accident could take anywhere from a year to 18 months.
"Our ultimate goal is to find out what happened, to issue recommendations to keep anything like this from happening again," said Sumwalt.
The boats operate on land and water and are popular with duck-whistling tourists.
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