An EgyptAir flight with 66 passengers and crew members heading from Paris to Cairo crashed into the Mediterranean Sea near the Greek island of Crete early on Thursday morning, after first disappearing from radar screens, according to Egyptian and Greek officials.

Both Egypt’s aviation minister and the head of Russia’s top domestic security agency said that the crash was most likely a terror attack, the Associated Press reported.

EgyptAir said it received an emergency signal from the plane at 4:26 a.m., two hours after it disappeared from radar screens. The plane’s passengers included 30 Egyptians, 14 French nations, and nationals from 10 additional countries. Among them were also one child and two infants, as well as 10 crew members.

“The theory that the plane crashed and fell is now confirmed after the preliminary search and after it did not arrive at any of the nearby airports,” said an anonymous senior aviation source, Reuters reported. “All causes for the disaster are open, whether it is a major technical fault or a terrorist action or any other circumstance. This will be ascertained when we inspect the plane’s wreckage and transcribe its black boxes.”

The EgyptAir crash brought back memories of the crash of a Russian passenger plane crash in the Sinai desert in October 2015, in which 224 people were killed. Russia said that crash was caused by a bomb, and the Islamic State terror group claimed responsibility for that attack.