The department says in a statement that officials from the U.S. Embassies in Kuala Lumpur, Malaysia, and Beijing are in contact with families of the passengers. The department says it's working to determine if other U.S. citizens may have been on the flight.
No additional information was released.
The aircraft went missing early Saturday on a flight from Malaysia to Beijing. Vietnamese air force planes report spotting a pair of large oil slicks in the area where the Boeing 777 went missing.
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.