UPDATE: Officials said Monday morning that oil slicks and a floating object are not from the missing flight. Read more here.

Vietnam authorities have reportedly spotted an object floating in the ocean near two oil slicks that were discovered more than 24 hours ago.

Officials can’t confirm that the object is debris from the missing Boeing 777, but are sending boats to the scene to investigate.

The search continues for the flight from Malaysia which was headed to Beijing when it fell off the radar and disappeared. There were 239 people aboard the plane.

Malaysian officials say radar signals show that the plane may have tried to turn back before vanishing. The flight crew did not notify ground control about a change of course.

Investigators are now focusing on two passengers who were traveling with stolen passports – an Italian-issued document under the name Luigi Maraldi and an Austrian passport bearing the name Christian Kozel. Both were stolen in Thailand.

The tickets were bought together almost simultaneously, and they had onward flights from Beijing to Europe.

Interpol says that no country checked its database for information about the two passports ahead of the flight.

Investigators are also looking at five passengers who checked in but didn’t board the plane.

Three Americans were among the people aboard the plane. Philip Wood, 50, was the only adult American on the flight. The other two Americans aboard were children, ages 2 and 4.

The weather was fine and the plane was at cruising altitude at the time of its disappearance. Only 9 percent of fatal accidents happen when a plane is at cruising altitude, according to a statistical summary from Boeing.

The plane was inspected 10 days ago and was “in proper condition.”

Read previous coverage on missing Malaysia Airlines flight:

UPDATE: Texas-Based Company Says 20 Employees Were on Missing Flight

Search Underway for Missing Malaysia Airlines Flight Carrying 239 People