European travel suffered a fresh blow to confidence in the early hours Thursday as EgyptAir flight 804 was lost over the Mediterranean Sea en-route from Paris to Cairo with 66 passengers and crew on board.

The plane, an Airbus A320, was flying at about 37,000 feet at about 3:30 a.m. local time when it lost contact with radar. An international search underway Thursday was focused off the Greek island of Carpathos.

Officials stressed Thursday it was too early to reach conclusions about what happened to the plane, with prosecutors in Paris issuing a statement saying that "no hypothesis is privileged or pushed aside for the moment." A Greek minister, according to CNN, told reporters that the airplane "swerved and then plunged" before falling into the Mediterranean, a fact which if true could support any number of theories as to the cause of the crash.

But terrorism is certainly front of mind, as Europeans have endured numerous incidents of late including a March attack in Brussels that killed more than 30 and a November attack in Paris that killed 130. Also in March, a domestic EgyptAir flight was hijacked and forced to land in Cyprus.

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Any indication that this plane was forced down could add to the pressure on travel-related businesses. Analysts have warned there could be a business impact from previous attacks, with travel intelligence provider Forwardkeys in April estimating that international arrivals into Europe would fall 5% in the second half of April compared to a year prior based on airplane seat bookings. Brussels was expected to be down 24% year over year.

But so far the financial impact has been limited. Atlanta-based Delta Air Lines (DAL) - Get Report  estimated a $5 million impact to its business from the Brussels attack, with much of that cost attributable to flight cancellations following the attack. Delta said European sales "recovered quickly" following the events in Brussels.

Markets continued to show resilience on Thursday. Leading airline stocks in Europe were down marginally as wider benchmark indices fell.

In Frankfurt, Lufthansa (DLAKY)  was down 0.10%. In London, British Airways parent International Consolidated Airlines ICAGY was down almost 0.9%. Air-France KLM (AFLYY)  was down 0.5% but discount carrier Ryanair (RYAAY) - Get Report rose 0.20%.