NAIROBI, Kenya — A fire in the generator room of a cruise ship on Monday cloaked more than 1,000 people in darkness and set the vessel adrift in a region of the Indian Ocean where Somali pirates have been active, officials said.

No casualties were reported, but the accident aboard the Costa Allegra occurred about six weeks after the Concordia — another Italian cruise ship owned by the same company — capsized off Italy, killing 25 people and leaving seven missing and presumed dead.

Tug boats from the island nation of Seychelles were steaming to the powerless ship. But the tugs were not expected to reach it until Tuesday afternoon at the earliest, and a top Seychelles military official said he could not yet say when the cruise ship might be brought back to port.

“The passengers are fine,” Italian Coast Guard Cmdr. Cosimo Nicastro told SkyTG24 TV. But the fire left the cruise liner “without propulsion,” meaning the ship, with 636 passengers and 413 crew members aboard, was adrift in the sea because the engines weren’t working, he said. But “the fire danger is over,” Nicastro said.

Costa Crociere SpA, which is based in Genoa, Italy, said in a statement that its ship was about 20 miles (12.5 kilometers) from Alphonse Island, one of the atolls in the Seychelles, a nation of islands and atolls that is a popular tourist destination.

Seychelles officials were investigating evacuating passengers using the small airstrip on Alphonse Island.

The general region where the cruise ship was adrift — off the coast of Tanzania — has seen a rash of attacks by Somali pirates, but they have never hijacked a cruise ship. A Seychelles official said armed guards are on board the cruise ship. She said that is standard practice for cruise ships “these days.”

“If pirates attack, the armed guards on-board will respond. But as far as I am aware, no pirates have been sighted in the area,” said Seychelles presidential spokeswoman Srdjana Janosevic.

Costa Crociere said in a statement that after the fire began in its Costa Allegra’s electric generator room, “the special firefighting units intervened to extinguish it.”

“The fire did not spread to any other area of the ship. There were no injuries or casualties,” the statement said. It did not say what caused the fire.

The cruise company said that a general emergency alarm was “promptly sounded” as a precaution, and that all passengers and crew not involved in the emergency reached assembly points.

The Florida-based Carnival Corp. is the parent company of Costa Crociere.

After the Concordia cruise ship struck a reef off Italy’s tiny Tuscan island on Jan. 13, its captain was arrested and several other officials were placed under investigation. When the Concordia listed to one side, many people hadn’t been evacuated on life boats and some jumped into the sea. Concordia passengers said that the order to evacuate came about an hour after the ship was speared by the reef and started taking on water.

On Monday, Italian coast guard officials dispatched cargo ships near the Costa Allegra to help the cruise ship and its passengers.

The Seychelles coast guard and air wing mobilized, and an aircraft was flying over the ship late Monday evening, said Janosevic. The island’s port authority sent two tugs to the stricken ship.

“And there are fishing vessels in the vicinity, large ones, that are going to provide support as well,” Janosevic said. “They have assistance coming to them.”

The Allegra had left northern Madagascar, off Africa’s southeast coast, on Saturday and was cruising toward the port of Victoria, Seychelles’ capital, when the fire erupted. Costa said the Allegra had been due in Victoria on Tuesday.

Lt. Col. Michael Rosette, the deputy chief of Seychelles defense forces, told The Associated Press in Nairobi that the tugs would take the cruise ship back to Port Victoria, but he could not provide the timing of that arrival. The coast guard told Seychelles Broadcasting Corp. TV that the tugboats would not reach the Costa Allegra until Tuesday afternoon.

“We don’t know yet because the tug is on the way. Once they reach the ship, we can establish a speed. We don’t know how fast it will be able to go yet,” Rosette said.

Nicastro said it would take time for the tugs to reach the Allegra and then get it to port, estimating that the arrival in the Seychelles capital would unlikely be before afternoon Tuesday.

The ship was some 235 nautical miles from the Seychelles capital as of 8 p.m. local time Monday.

The Allegra was built in Italian shipyards in 1992, is 615-feet (188 meters) long, and has eight passenger decks and 399 cabins.