Travel stocks fall after Brussels attacks

Travel companies saw their stocks fall Tuesday as the industry grappled with the attacks in Brussels.

Shares of American Airlines and Delta Air Lines closed about 1.5 percent lower, while hotel operators Starwood Hotels and Marriott International saw their stocks fall 0.4 percent and more than 1.9 percent, respectively. United Continental Holdings, which owns United Airlines, saw its stock drop over 1 percent.

Brussels, Belgium's capital, was hit by a series of deadly explosions that left at killed at least 31 people. One of the explosions took place in Brussels' main airport of Zaventem and another at the Maelbeek metro station. Brussels Airport CEO Arnaud Feist said that all Wednesday flights were later canceled.

The travel industry is trying to reassure customers following the attacks.

American Airlines said it would cancel flights to Brussels for Wednesday and Thursday, saying it is "taking care of our employees and customers in Brussels after this morning's events. At this time, there are no reported injuries to our employees." United said it would waive change fees and differences in fares for customers choosing to rebook flights to Brussels through April 1, as it reaches out to affected employees.

VRT said the airport bombing was a suicide attack.

Delta, Starwood and Marriott also issued statements confirming the safety of their employees and customers.

Starwood has four hotels in Brussels, while Marriott has five.

"Given the ongoing situation, we are sensitive to the potential impact on our guests. As such, we are waiving cancellation fees for guests holding existing reservations at all four Marriott properties in Brussels for the immediate future," Marriott said.

Travelers who bought insurance should check to see if the policy will kick in to cover nonrefundable costs of rescheduling or canceling the trip. Policies often have a specific terrorism clause.

Requirements vary, but typically, you're covered to cancel your trip if the attack occurred in a city on your itinerary or within a certain distance (say, 50 miles) of your itinerary, said Megan Singh, director of marketing for insurance comparison site Squaremouth.

Most policies also require the State Department to deem an event a terror attack, which hasn't happened yet for the Brussels explosions, she said.

"In every case, you need to buy the policy before the attack occurs," Singh said. Travelers can still buy policies to cover the possibility of future attacks, however. "Most terrorist attacks are looked at as separate events," she said.

See how airline stocks are doing.

— CNBC's Kelli Grant contributed to this report.