(Reuters) – U.S. airlines including Delta, United and American canceled flights on Tuesday after two deadly blasts in a packed departure area of the Brussels Airport at Zaventem.

A suicide bomber blew himself up in one of the Tuesday morning airport explosions, which public broadcaster VRT said killed 14 people. Another 20 were killed when a blast tore through a rush-hour metro train in the European capital shortly afterward, VRT said.

Video at the airport, which was shut down, showed devastation, with ceiling tiles and glass scattered across the floor. Some passengers emerged from the terminal with blood spattered over their clothes.

While there were no credible threats to U.S. airports or transportation hubs, police presence was beefed up as a precaution in the nation’s major cities, including New York, Washington and Los Angeles.

Delta Air Lines Inc said its flight DL42 from New York to Brussels was diverted to Amsterdam. Another flight, DL80 from Atlanta, had landed safely at the Zaventem airport and was parked remotely while the airline’s local staff helped passengers exit safely.

News of the multiple blasts, which have Brussels on lockdown and have snarled some cross-border traffic, sent shares of U.S. airlines and travel-related companies lower. Delta was down 2.1 percent at $49.04 in morning New York Stock Exchange trading, while United Continental Holdings Inc fell 1.4 percent to $69.34.

United Airlines, which had two flights due in Brussels on Tuesday morning, said both landed there safely.

The company said it was suspending all remaining flights to and from Brussels.

American Airlines Group Inc said it had canceled flight 751 from Brussels to Philadelphia and would accommodate its passengers when the airport reopens.

The explosions did not occur where American’s check-in operates, the company said, so all of its airport employees are safe and accounted for.

Starwood Hotels & Resorts Inc said all of its hotels in Brussels were on lockdown, along with the rest of the city.

Facebook Inc said it had activated its “safety check” feature, which allows its users to check on friends who were in the area of the blasts.

(Reporting by Sayantani Ghosh in Bengaluru; Editing by Ted Kerr and Lisa Von Ahn)