Over three full days since it first went missing, Malaysian authorities now believe a lost Malaysia Airlines jetliner may have crashed over the Malacca Strait, after it apparently steered off course and flew hundreds of kilometers west of its planned destination, a senior officer told Reuters Tuesday.

“It changed course after Kota Bharu and took a lower altitude, the senior military officer told Reuters. “It made it into the Malacca Strait.”

Flight MH370, a Boeing 777, had 239 people on board when it vanished off radar screens early Saturday morning en route to Beijing from Kuala Lumpur, triggering a massive international search effort.

The new report would seemingly rule out the possibility that the jetliner encountered any technical difficulties, as it apparently managed to fly nearly 500 kilometers (350 miles) after losing contact with civil air traffic control.

Authorities began their hunt at the plane’s last known location, a spot in the seas between Malaysia and Vietnam. With no debris found, they have systematically expanded their search to include areas where the plane could have in theory ended up given the amount of fuel it had on board.

Also Tuesday, authorities said two people who boarded the flight using stolen passports were Iranians who had purchased tickets to Europe. Their appearance on the flight had raised speculation of a possible terrorist link.

Malaysian police chief Khalid Abu Bakar said investigators had determined one was a 19-year-old Iranian, Pouria Nourmohammadi Mehrdad, and that it seemed likely he was planning to migrate to Germany.

“We believe he is not likely to be a member of any terrorist group,” Khalid said.

Interpol identified the second man as Seyed Mohammed Reza Delavar, a 29-year-old Iranian, and released an image of the two boarding a plane at the same time. Interpol Secretary General Ronald K. Noble said the two men traveled to Malaysia on their Iranian passports, then apparently switched to their stolen Austrian and Italian documents.

He said speculation of terrorism appeared to be dying down “as the belief becomes more certain that these two individuals were probably not terrorists.” He appealed to the public for more information about the two.