U.S. investigators are preparing to head to Ukraine to assist in the aftermath of a Malaysian airliner that was shot down over eastern Ukraine with 298 people on board, an official said on Friday.

FBI and U.S. National Transportation Safety Board personnel are headed to the region to serve in an advisory role for the investigation of Thursday's incident, the U.S. official said.

FBI spokesman Paul Bresson said that agency would send at least one investigator but that it was not yet clear when the official would go or if other staff would be needed to assist, citing the "still fluid situation."

"The facts, as they are uncovered, will dictate our actions," Bresson said.

An NTSB representative did not immediately respond to a request for comment on the agency's plans.

The flight had had 189 Dutch passengers, 29 Malaysian, 27 Australian, 12 Indonesian, nine British, four German, four Belgian, three Filippino, one Canadian and one New Zealander on board as well as four of as yet unidentified nationalities.