(CNN) -- A tourist boat with more than 30 people on board overturned on the Delaware River at Philadelphia, Pennsylvania, Wednesday after it was hit by a barge, Philadelphia police and the Coast Guard said.
"We confirmed that there were 37 people on board, 35 passengers and two crew. As of right now we have confirmed that 35 people have been recovered. There are two people missing," said David Umberger, the Coast Guard's civilian search and rescue controller for the area, shortly after the accident.
The two missing people are a 16-year-old female and a 20-year-old male, Lt. Frank Vanore of the Philadelphia Police Department told reporters later Wednesday afternoon.
Vanore said that the boat had "mechanical trouble" and the engine shut down after a fire on board. While the boat was in the river and waiting for help, it was hit by a barge, he said.
The National Transportation Safety Board said Wednesday night it had sent an investigative team to the scene.
The Coast Guard's Umberger said the search was continuing for the missing.
"We have all of our port partners engaged in that search-and-rescue case, including the state police, Philly police, fire department, good samaritans and the Coast Guard," he said.
Deputy Commissioner William Blackburn of the Philadelphia police told CNN that searchers located the boat in about 50 feet of murky water but it was too dangerous to send divers down.
The boat is upright on the bottom of the river, Blackburn said, adding that it has been marked by a buoy and divers will be sent down when it is deemed safe.
One area hospital, Hahnemann University Hospital, reported eight patients -- two adults, three children, three teenagers -- were brought in after the incident. Two other passengers on the boat also were taken to the hospital but declined treatment, Hahnemann Hospital spokeswoman Coleen Cannon said.
Of the eight patients, one adult and two children were discharged a few hours after the incident, she said.
CNN's Vivienne Foley, Susan Candiotti, Steve Kastenbaum, Brian Vitagliano and Jesse Solomon contributed to this report.