A private jet flying to Germany changes course and crashes into the Baltic Sea in Latvia.

Authorities said a private jet carrying four people that was supposed to land in Germany but continued to fly across Europe after air traffic controllers failed to make contact crashed Sunday off the coast of Latvia.

The plane was “flying between Spain and Cologne, but when it changed course, air traffic controllers were unable to make contact,” according to the Latvian civil aviation agency.

As the Austrian-registered plane continued to fly across northern Europe, fighter jets from Germany, Denmark, and Sweden scrambled to contact the crew in the air, “but they saw no one,” Swedish search and rescue operation leader Lars Antonsson told AFP.

The Cessna 551 plane flew over Swedish airspace in the Baltic Sea before crashing into the water near Ventspils shortly before 8:00 p.m. (1800 GMT).

The plane flew relatively steadily until it approached the Latvian coast, at which point it quickly lost altitude.

According to Antonsson, the plane crashed “when it ran out of fuel.”

The nationalities of the four on board were unknown at the time.

“Rescue teams from Latvia, Lithuania, and Sweden are working at the crash site,” the Latvian aviation agency said.

“No human remains have been discovered,” Antonsson of Sweden added.

It is unknown what caused the plane to deviate from its intended path.

“We have no explanation; we can only speculate,” Antonsson said of what happened, “but they were incapacitated on board.”