WASHINGTON, June 28 -- The White House on Tuesday condemned "in the strongest possible terms" the attack at Ataturk airport in Istanbul that killed at least 36 people.

"Ataturk International Airport, like Brussels airport which was attacked earlier this year, is a symbol of international connections and the ties that bind us together," said the White House in a statement, adding that the United States remains steadfast in supporting Turkey and other allies around the world.

Meanwhile, the U.S. Federal Aviation Administration on Tuesday grounded all flights between the United States and Istanbul, Turkey's most populous city, after the attack.

It remains unclear how long the order would last.

At least 36 people were killed and hundreds of others injured in two explosions that hit the airport in Istanbul on Tuesday night local time.

Three suicide bombers were involved in the attack. One attacker opened fire in the departures hall with an automatic rifle, before all three blew themselves up in or around the arrivals hall a floor below, witnesses and officials said.

A Turkish official was quoted as saying on Twitter that the vast majority of casualties are Turkish citizens, with foreigners among the dead and wounded.