(Reuters) — Investigators seeking the cause of a ferry accident near Wall Street that injured more than 50 people will reportedly look into possible mechanical failure, which was blamed for one of the boat's past docking crashes.

National Transportation Safety Board inspectors were in Highlands, N.J., on Thursday where the Seastreak Wall Street was towed to its berth following Wednesday's morning rush-hour crash, said Coast Guard spokeswoman Jetta Disco.

The high-speed commuter ferry was carrying more than 300 passengers from New Jersey when it crashed into a pier during a docking approach, injuring 57 people, authorities said. One patient remained in critical condition on Thursday, according to NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

"It's a pretty good-sized hole," Ms. Disco said of the gash torn into the 141-foot catamaran, which was traveling at 10 to 12 knots, or about 11.5 to 14 miles per hour, when it hit the pier.

The five-member crew will undergo drug tests, having passed breathalyzer tests following the accident, Ms. Disco said.

Wednesday's scenes of passengers on stretchers on the pier recalled earlier landing crashes involving the nearby Staten Island Ferry, including one in October 2003 which killed 11 and injured dozens, and one in May 2010 that injured about 40.

The ferry pilot in the 2003 crash and his supervisor were each sentenced to more than a year in prison for their roles in the accident. The pilot, Richard Smith, had passed out at the helm. He had taken painkillers the night before for a bad back.

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Among possible causes under scrutiny in Wednesday's crash is mechanical failure after the boat struck a buoy about 100 feet from dock before the hard landing, according to local media.

Seastreak Wall Street had at least two previous docking accidents, in 2009 and 2010, including one blamed on mechanical failure, according to a Coast Guard website.

The accident occurred as commuters lined up to disembark and head to work. Many were thrown to the deck by the impact.

The ferry is run by Seastreak, a company owned by the Barker and Tregurtha families, who also own the Interlake Steamship Co., Mormac Marine Group Inc., and Moran Towing Co., the largest tug and barge operator on the East and Gulf coasts, according to the company's website.