What is certain is that “something very sudden happened”:

Malaysia Airlines Flight MH370 was en route from Kuala Lumpur to Beijing when it lost contact with air traffic controllers around 2:40 a.m. local time Saturday, two hours after takeoff, the airline said.

The airline’s chief executive, Ahmad Jauhari Yahya, told a news conference in Kuala Lumpur that there was no distress call or bad weather report from the pilots before the plane lost contact with air control 120 nautical miles (140 miles) off the east coast of Kota Bharu, Malaysia.

As the search-and-rescue effort got underway, in addition to Vietnamese aircraft, China sent two ships to assist, state-run CCTV reported, while Singapore dispatched a C-130 aircraft. Malaysia sent three maritime enforcement ships, a navy vessel and three helicopters, a Malaysian Maritime Enforcement Agency official told Reuters.

Mikael Robertsson, cofounder of FlightRadar24, which tracks about 120,000 flights per day with 3,000 receivers around the world, said the last transmission it recorded from the flight was at 35,000 feet. While it’s possible the plane veered into an area too far away from receivers to track it, he said that was unlikely.

“In this case, we have quite good coverage,” he said. “We had a very good stable signal and it just disappeared …. I don’t want to speculate, but something very sudden happened.” FlightRadar representatives also said they believed the plane had lost radar contact about 40 minutes into the flight, not two hours as the airline said.

The recent terror attack at a train stationin China’s Xinjiang province by Muslim terrorists that killed 29 and wounded more than one hundred people suggests that terrorism may very well be a possibility in the downing of the Malaysia Airlines jet. But it may be many weeks or months before investigators will be able to confirm exactly what happened to cause the 777 to drop out of the sky.