Vietnamese navy planes have spotted what could be fragments from the missing Malaysia Airlines jet that disappeared almost two days ago.
Officials said it was too dark to be certain the objects were from Flight MH370, which had 239 people on board.
A multinational team is searching for wreckage and ships will try to confirm the find after dawn.
Investigators are also checking CCTV footage of two passengers who were travelling on stolen passports.
Malaysian military officials said on Sunday that the plane may have turned back from its scheduled route shortly before vanishing from radar screens, further deepening the mystery surrounding its fate.
Relatives of the missing passengers have been told to prepare for the worst.
More than a day and half after Malaysia Airlines Flight MH370 went missing, no confirmed debris from the plane had been found, and the final minutes before it disappeared remained a mystery.
The plane, which was carrying 239 people, lost contact with ground controllers somewhere between Malaysia and Vietnam after leaving Kuala Lumpur early Saturday morning for Beijing.