By Justin Sink - 07/17/14 08:00 PM EDT
At the top of an infrastructure speech in Delaware Thursday, President Obama offered "any assistance we can" with the investigation into a crashed passenger airline near the Ukraine-Russia border.
"Obviously, the world is watching reports of a downed passenger jet near the Russia-Ukraine border," Obama said. "It looks like it may be a terrible tragedy."
Malaysia Airlines Flight 17, a Boeing 777 traveling from Amsterdam to Kuala Lampur, had 280 passengers and 15 crew members on board. Ukrainian authorities have accused pro-Russian separatists battling government forces in the country's eastern regions of shooting down the plane, although the U.S. has said it cannot confirm reports on the cause of the crash.
The president said the nation's "first priority" was "working to determine whether or not there were American citizens on board."
"Our thoughts and prayers are with all the families of the passengers, wherever they call home," Obama added.
Earlier Thursday, the White House said Obama and Russian President Vladimir Putin had discussed reports of the crash during a telephone call to discuss new sections announced by the U.S. on Wednesday.
Press secretary Josh Earnest said the conversation occurred near the end of the call, requested by Moscow.
The Kremlin said Putin "informed the U.S. president of the report from air traffic controllers that the Malaysian plane had crashed on Ukrainian territory, which had arrived immediately before the phone call" in a statement posted to its website.
President Obama also called Malaysian Prime Minister Najib Thursdsay to express condolences to the people of Malaysia for the terrible loss of Malaysia Airlines Flight 17 in Ukraine and the families who lost loved ones, according to a White House statement.
This story was originally published at 2:54 p.m. and updated at 8:00 p.m.