A private jet reportedly carrying a family has crashed into the Baltic Sea with four people on board, officials say.
A rescue effort is underway as the Swedish Coast Guards confirmed they have found a wreckage of the Austrian-registered Cessna 551 aircraft.
The chance of finding survivors is minimal, the Maritime and Air Rescue Centre's Lars Antonsson stated.
According to German Bild, a pilot, a woman, a man and their daughter were all flying when the plane came down in mysterious circumstances during its erratic flight but other reports say six people were on board.
Shortly after take-off, the plane reported that there was a problem with the pressure in the cabin. Contact was lost, just outside the Iberian Peninsula.
In a statement on its website, the Civil Aviation Agency confirmed that an "aviation accident" has occurred in the sea near Ventspils.
Nato pilots and Swedish officials tracking the plane could see no one in the cockpit.
"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 warplanes 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.
The NATO fighter aircraft took off on Sunday evening to follow a Cessna plane, a Lithuanian airforce spokesperson said.
It turned twice, at Paris and Cologne, before heading straight out over the Baltic, passing near the Swedish island of
Gotland.
The aircraft are from the NATO Baltic Air Police mission in Amari airfield in Estonia, the Lithuanian airforce says.
The mission in the airbase currently consists of four Eurofighter jets of the German Air Force, according to NATO.
She did not say how many jets there were or comment further.
The Austrian-registered Cessna 551 aircraft is flying from Jerez in southern Spain, from where it took off at 12.56 pm GMT without a set destination, according to the FlightRadar24 website.
At 5.37 pm GMT it was listed on the tracker as rapidly losing speed and altitude.
Latvia said it had sent ships to the scene.
"Our ships are on the way to the position where the plane crash happened," said Liva Veita, spokesperson of the Latvian
Navy.
A Stena Line ferry travelling from Ventspils to Norvik in Sweden was also redirected to the crash site, according to the MarineTraffic website.
