NEW YORK - A commuter ferry carrying hundreds of people from New Jersey to New York City hit a slip at a lower Manhattan pier Wednesday, then kept going and smashed into a second slip, injuring at least 57 people, two of them critically.

One person was hurtled through a glass door and another fell down a flight of stairs as the Seastreak Wall Street, a triple-decker ferry carrying 326 passengers and five crewmembers, jerked to a stop, officials said. The impact tore a gash in the right front of the boat, which had left New Jersey at 7 a.m. CST for the 45-minute trip to the Wall Street area.

Most passengers said the ride had been normal and that people had lined up as usual near the front of the boat to disembark quickly as it neared Pier 11 on its second run of the day. Suddenly, there was a loud bang followed by a strong jolt.

"We just tumbled on top of each other. I got thrown into everybody else. ... People were hysterical, crying," said Ellen Foran, of Neptune City, N.J.

Dee Wertz, who was waiting for the ferry, saw the impact. "It was coming in a little wobbly," Wertz said. "It hit the right side of the boat on the dock hard, like a bomb."

Within minutes, emergency workers arrived at the pier and turned it into a triage center, where for nearly two hours they treated the injured strapped onto stretchers and laid side by side on the ground. Other passengers walked away, some with bandages covering wounds.

The cause of the crash was being investigated. The 140.7-foot-long catamaran had undergone renovations last summer to replace its engine system, which involved removing large sections of the hull to install new propellers and rudders. The work reduced the ship's weight and speed but improved its fuel efficiency, said Sea- streak's president, James Barker. "You're looking at the greenest ferry in America," he said.

Barker, who called it "a terrible day for all of us," said the captain has been with Sea-streak about 10 years and was at the controls. The boat has been involved in two previous incidents, in 2009 and in 2010, both minor. It was the most serious ferry accident in New York City since October 2003, when a Staten Island Ferry smashed into a Staten Island terminal after leaving lower Manhattan. Eleven people died and more than 70 people were injured in the crash. It was blamed on the pilot, who was on painkillers and fell asleep at the controls.

The Associated Press contributed to this report.