President Barack Obama said Thursday while discussing transportation funding in Delaware that the downed Malaysian passenger airplane over Ukraine might be a "terrible tragedy." "Right now we're working to determine whether there were American citizens on board. That is our first priority," said Obama. Ukrainian President Petro Poroshenko said the downing of the Malaysia Airlines plane carrying 295 people was an act of terrorism. The plane was flying at an altitude of 10,000 meters when it was hit by a missile, said adviser to Ukraine's interior minister Anton Gerashenko. At least 22 bodies have been found at the crash site near the Russian border where government and pro-Moscow separatists have been fighting, according to the Associated Press. Obama head spokesman Josh Earnest said Obama was on a phone call with Russian President Vladimir Putin when the news of the downed airplane broke but did not disclose remarks from either of the two leaders. The presidents spent the rest of the phone call discussing the situation in east Ukraine and U.S. sanctions against Russian individuals. "I've directed my national security team to stay in close contact with the Ukrainian government. The United States will offer any assistance we can to help determine what happened and why, and as a country our thoughts and prayers are with all the families of the passengers wherever they call home," said Obama.