By Nick Valencia, CNN

Passengers sleep on the deck of the Norwegian Dawn after a power failure on the ship.

STORY HIGHLIGHTS

• The Norwegian Dawn lost power Friday about 95 miles off coast of Puerto Rico
• The power failure forced the ship to dock Saturday in San Juan
• About 2,400 passengers were vacationing on the ship, the cruise line said
• The cruise line chartered two planes to fly passengers back to Miami

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(CNN) -- An American cruise ship returning from a nine-day cruise around the Caribbean unexpectedly docked in San Juan, Puerto Rico, early Saturday after temporarily losing power earlier, a spokeswoman for Norwegian Cruise Line said.

"The ship had some technical difficulties when it was on its way back to Miami," spokeswoman AnneMarie Mathews said. She said she was unsure what caused the power outage.

The outage occurred around 9:30 a.m. Friday on the Norwegian Dawn, about 95 miles off the north coast of San Juan, according to a statement from Norwegian. The Coast Guard and local authorities were contacted.

The crew was unable to restore power fully, forcing it to dock Saturday in San Juan at about 7:30 a.m., the statement said.

About 2,400 passengers were vacationing on the ship, the cruise line said.

Passenger Barry Doft, 64, of Aventura, Florida, said, "Hundreds of people spent [Friday] night sleeping outside on the open deck because there was no air conditioning in the cabins and the temperature inside the ship became hot and uncomfortable."

Mathews could not confirm passengers slept on the deck, but did say the ship was operating with limited power and that the ship's central air unit was affected. No injuries were reported from the situation, she said.

The cruise line chartered two planes to fly passengers back to Miami, Mathews said.

Because of the technical difficulties, Norwegian Dawn's five-day Western Caribbean cruise departing Miami on Sunday, was cancelled, the cruise line said.