People go through security at JFK Airport the day before Thanksgiving in New York City. Spencer Platt/Getty Images

Shares in international air carriers came under pressure Thursday, underperforming the day’s weaker global stock markets, after Cairo-bound EgyptAir Flight 804 disappeared over the Mediterranean Sea earlier in the day. Fears that the plane was taken down in a terrorist attack gave investors jitters over the potential impact on global air travel.

The drop in airline stocks was mostly steeper than the trend in broader indexes on both sides of the Atlantic. The FTSEurofirst 300 Index ended the day 1.19 percent lower while Wall Street’s S&P 500 ended the day down 0.4 percent.

The logos of EgyptAir and other carriers are seen on a computer terminal screen in Barcelona, Spain, March 19, 2016. Joan Cros/NurPhoto via Getty Images

The cause of the crash, as well as the location of the crash site, was unknown Thursday evening, U.S. East Coast time. Virtually every major global carrier started the trading day down significantly, a typical reaction to terrorist attacks. Tourism-related stocks plunged after the attacks in Brussels in December, though the market reaction to the EgyptAir Flight 804 disappearance has been more subdued.

EgyptAir travel stocks
EgyptAir planes are seen on the tarmac at Cairo's airport on Thursday, May 19, 2016, after an EgyptAir flight from Paris to Cairo crashed into the Mediterranean on with 66 people on board. The crash, and concern the plane might have been taken down in a terrorist act, weighed on airline stocks Thursday. KHALED DESOUKI/AFP/Getty Images

Another factor hurting travel stocks was a report released before markets opened in Western Europe from Thomas Cook. The major British travel agency said in its half-year report that summer bookings are down 5 percent compared to last year. An increase in travel to the U.S. and Spain this summer wasn’t enough to offset a steep decline in travel to Turkey and a retreat in Belgium compared to last year.

Stock in hotel groups Accor, TUI and InterContinental also closed down by as much as 2.9 percent.

Here’s where stocks in the major airlines closed on Thursday:

American Airlines Group: Down 1.4 percent.

Delta Air Lines: Down 1.7 percent.

United Continental Holdings: Down 2.8 percent.

Deutsche Lufthansa: Down 1.3 percent.

Air France-KLM: Down 1.1 percent.

International Consolidated Airlines (British Airways, Iberia): Down 1 percent.

Southwest Airlines: Down 1.7 percent.

China Southern Airlines: Down 1.8 percent.

All Nippon Airways (ANA): Down 0.8 percent.

Qantas Airways: Down 2.1 percent.