Traces of explosives have been found on some of the victims of an EgyptAir flight from Paris that crashed in the Mediterranean Sea in May, Egypt’s government said Thursday, a finding that could deal another major blow to the country’s vital tourism sector.

A Civil Aviation Ministry statement said a criminal investigation will be launched into the crash of Flight 804, which killed all 66 people on board and came just seven months after a Russian passenger plane was blown up over the Sinai Peninsula in an attack claimed by the Islamic State group.

That attack, which killed all 226 people on board in October 2015, led to widespread flight cancellations and emptied out Egypt’s Red Sea resorts. Tourism has been sharply down in much of the rest of the country following years of unrest unleashed by the 2011 uprising that toppled autocrat Hosni Mubarak.

Egypt has never officially said what caused the downing of the Russian plane. But a local IS affiliate said it blew up the plane with a bomb smuggled on board, and Russia said the aircraft was likely downed by explosives.

No one has claimed to have brought down Flight 804. France opened a manslaughter inquiry into the crash in June, but made clear it was an accident investigation, not a terrorism investigation.

An official at the office of Egypt’s top prosecutor said Egyptian criminal investigators would now coordinate with their French counterparts. The official spoke on condition of anonymity because he was not authorized to brief reporters.

Authorities have said that before dawn on May 19, the Airbus A320 lurched left, then right, spun all the way around and plummeted 38,000 feet (11,582 meters) into the Mediterranean as it was approaching Egypt’s northern coast. The plane never issued a distress call.

Experts have suggested a rogue passenger might have taken control of the plane or that there may have been a struggle between the pilots.

But three European security officials said at the time that the flight’s passenger manifest contained no known names on terror watch lists, often used by European and American security and law enforcement agencies.

Egyptian investigators said in July after analyzing a recovered cockpit voice recorder that the pilots of Flight 804 tried to extinguish a fire on board the aircraft. The recordings were consistent with data that had previously been recovered from the plane’s wreckage that showed heat, fire, and smoke around a bathroom and the avionics area, they said.

France’s accident investigation agency has said that smoke detectors went off during Flight 804’s final moments.

Industry publication Aviation Herald also has reported that sensors detected smoke in the plane’s lavatory, as well as a fault in two of the plane’s cockpit windows in the final moments of the flight.

Egyptian independent aviation investigator Hany Galal said Thursday’s findings explain the fact that the pilots did not issue any distress calls and the aircraft’s erratic movements before it crashed.

IS has carried out several attacks in recent years, mainly in the Sinai, where it is based, but also on the Egyptian mainland. The group claimed responsibility for a suicide bombing at a Cairo church on Sunday, which killed at least 24 people, mainly women, and wounded nearly 50.

In recent months Egypt has spent millions of dollars trying to restore international confidence in its airport security measures. Russia had suspended all flights to Egypt after the October crash, while Britain cancelled flights to Sharm El-Sheikh, the Red Sea resort from which the airliner took off.

(AP)