A private Cessna plane crashed off the coast of Latvia on Sunday evening, Sweden's rescue service said, after NATO scrambled jets to follow its erratic course.
The Austrian-registered Cessna 551 aircraft was flying from Jerez in southern Spain, from where it took off at 1256 GMT without a set destination, according to FlightRadar24 website.
It turned twice, at Paris and Cologne, before heading straight out over the Baltic, passing near the Swedish island of Gotland. At 1737 GMT it was listed on the flight tracker as rapidly losing speed and altitude.
"We've learned that the plane has crashed (in the ocean) north-west of the town of Ventspils in Latvia," a spokesperson for Sweden's rescue service said. "It has disappeared from the radar."
German and Danish war planes had earlier been sent to inspect the aircraft as it passed through those countries' airspace, but were unable to make contact, Johan Wahlstrom of the Swedish Maritime Administration said.
"They could not see anyone in the cockpit," he said.
German newspaper Bild reported that the plane was carrying the pilot, a man, a woman, and a person it described as a daughter, without sourcing the information.
A Lithuanian air force helicopter was dispatched to the crash site for search and rescue at neighbouring Latvia's request, a Lithuanian air force spokesperson said. Latvia said it had sent ships to the scene.