Four travelers were airlifted to Florida from the Bahamas for medical treatment Monday after a bus carrying Carnival Cruise Line passengers crashed on the island of Eleuthera, authorities said.

Three passengers sustained serious injuries, including arm and leg fractures, internal injuries and possible paralysis, Broward County’s fire and rescue department said in a statement.

The fourth patient's injuries were minor, the statement said.

Twenty-eight people were treated at a clinic in the Bahamas and were cleared to return to the ship, cruise officials told NBC Miami.

The bus was taking cruise passengers on a “shore excursion” tour operated by a third-party vendor that was not immediately identified, a spokesman for Carnival said. The bus was carrying 32 passengers from the Ecstasy cruise ship when it crashed, the spokesman said.

The cause of the crash was under investigation, the spokesman said, adding that the cruise — which left Jacksonville, Florida., on Saturday for a five-day trip — had been suspended.

Images from the crash scene showed the bus on its side and people sprawled out on the road.