Officials say the captain and pilot of a ferry that struck a jetty in Hyannisport, Massachusetts, leaving 18 people injured, have been placed on administrative leave as the Coast Guard continues to investigate.

A spokeswoman for the Woods Hole, Martha's Vineyard and Nantucket Steamship Authority said Wednesday that the captain and pilot tested negative for alcohol. The results of drug tests are pending.

Authorities say the ferry Iyanough hit the jetty and grounded on the rocks at the Hyannis Harbor entrance Friday night. The authority said there were 48 passengers, six crew members and three food service workers on board.

Authorities have said it's unclear what led to the crash. Bad weather, strong winds and choppy seas are cited as factors.

Fire officials say 15 people were taken to the hospital. A Cape Cod Hospital spokeswoman said the injured had been treated and released.