COPENHAGEN, Denmark (AP) — A ferry with some 300 people on board was stranded in the Baltic Sea on Tuesday after the ship’s engine failed and sent smoke pouring from the engine room, the Danish operator said.

The Regina Seaways was in international waters off Kalingrad, Russia’s Baltic Sea exclave between Poland and Lithuania when the breakdown occurred, Copenhagen-based DFDS Seaways said, adding that the smoke triggered the ship’s fire extinguisher system in the engine room.

Passengers assembled at muster stations in preparation for a possible evacuation, but the situation was under control and an evacuation wasn’t immediately necessary, DFDS spokesman Gert Jakobsen told The Associated Press. There were no reports of injuries.

“We are talking about a malfunction in the engine room that caused a lot of smoke,” Jakobsen said. “Right now we are inspecting the engine room to find out whether the ship can sail on its own or needs to be tugged.”

The ferry, which also had cars and trucks on board, was traveling from Kiel, Germany, to Klaipeda, Lithuania’s port city north of Kaliningrad. The crossing normally takes about 20 hours.

“On these kinds of crossings we have people from Germany, the Baltic countries and Russia. We cannot say now who was on board,” Jakobsen said.

The ship was about 85 kilometers (50 miles) from Klaipeda, said Vaidas Klumbys, another DFDS spokesman.

He said that on Tuesday afternoon “we received the information from the ship that it was undergoing vibrations and smoke rising from the engines.”

Russian state news agency Tass quoted Andrei Permyakov, head of the sea rescue coordination center in Kaliningrad, as saying that rescuers from Lithuania, Russia and Poland had responded.

Lithuania’s navy said one of its helicopters and three navy vessels were sent to the site in case an evacuation was necessary. The regional news agency, Baltic News Services, quoted Klumbys as saying “the weather conditions are not good.”

Forecasts for the southeastern part of the Baltic Sea said there were gale force winds, rain showers, poor visibility and risk of thunder storms in the region.

Jakobsen wasn’t aware of any rescue operation, saying there was no evacuation.

“But in this kind of situation, everyone steps in,” he said.

The Regina Seaways was built in 2010 and can carry up to 500 passengers.