WASHINGTON, Nov. 5 -- U.S. President Barack Obama on Thursday said there was a "possibility" that the crashed Russian passenger jet in Egypt was caused by a bomb aboard the plane.

"I think there's a possibility that there was a bomb on board. And we're taking that very seriously," said Obama in an interview with a radio station that was quoted by TV network CNN.

"We're going to spend a lot of time just making sure our own investigators and own intelligence community find out what's going on before we make any definitive pronouncements. But it's certainly possible that there was a bomb on board," he said.

White House spokesman Josh Earnest said earlier Thursday that the U.S. can not rule out the possibility of "terrorist involvement" in the jet crash that killed all 224 people onboard.

Earnest said the U.S. hadn't determined what caused the crash.

The Airbus A-321 operated by Russian airline Kogalymavia crashed early Saturday in the Sinai Peninsula shortly after taking off from Egypt's Red Sea resort Sharm el-Sheikh.