The National Transportation Safety Board tweeted that its investigators were gathering information about the cause of the crash.
A construction worker, who asked not to be named, told Reuters he was working nearby when he saw the 400-passenger ferry slam into the pier.
The boat was backing up and hit something and that's when everything went crazy.
The ferry that crashed is run by Seastreak, a privately owned company that also holds the Interlake Steamship Company, Mormac Marine Group, and Moran Towing, the largest tug and barge operator on the East and Gulf Coasts, according to the company's website.
More top news
The pilot of the missing MH370 plane plotted a course to the southern Indian Ocean on a home flight simulator, investigators have said.
Joe Campbell said he wanted to adopt Kiran Sheikh but was told he couldn't because he wasn't married.
Annual rail figures reveal the most overcrowded service in spring/autumn 2015, was an early morning train from Brighton to Bedford.