Two cargo ships collided in the North Sea off the German coast on Tuesday and several people were missing, German authorities said.

The ships, Polesie and Verity, collided in the early morning about 22 kilometers (14 miles) southwest of the island of Helgoland, Germany’s Central Command for Maritime Emergencies said.

One of the ships, the British-flagged Verity, apparently sank. The emergency command said one person was rescued from the water and was being given medical treatment, and rescuers were searching for several more people who were missing. It said the ship, which was 91 meters (299 feet) long and 14 meters (46 feet) wide, was headed from Bremen, Germany, to the English port of Immingham.

The other, bigger ship, the Bahamas-flagged Polesie, remained afloat with 22 people on board. It was heading from Hamburg to A Coruña, Spain.

Vessels supporting the rescue effort included a cruise ship, the Iona, that has doctors on board and could treat people if needed, the emergency command said. More medical personnel were being taken to the scene by helicopter.