President Obama says it is “a possibility” that a bomb downed a Russian passenger plane in Egypt’s Sinai Peninsula over the weekend, killing 224 people aboard. This comes as the BBC reports British investigators believe a bomb was placed in the aircraft’s baggage compartment just before takeoff. An affiliate of the self-proclaimed Islamic State has said it was responsible. Egypt and Russia have rejected this claim, saying there is no evidence to support it. On Thursday, White House Press Secretary Josh Earnest said the U.S. has not yet made a determination on the cause of the crash.

Josh Earnest: “There’s obviously an Egyptian-led investigation into this tragic incident that remains ongoing. At this point, the United States has not made our own determination about the cause of the incident. However, we can’t rule anything out, including the possibility of terrorist involvement.”