"At the moment we have no idea where this aircraft is right now," Malaysia Airlines Vice President of Operations Control Fuad Sharuji said on CNN's "AC360."
Subang Air Traffic Control lost contact with Flight MH370 at about 2:40 a.m. local time (1:40 p.m. ET Friday), Sharuji said.
Quest: Odd to lose contact while cruising
Plane loses contact with airline
"We tried to call this aircraft through various means," he said.
The Boeing 777-200 departed Kuala Lumpur International Airport at 12:41 a.m. and was expected to land in Beijing at 6:30 a.m., a 2,300-mile (3,700 kilometer) trip. It was carrying 227 passengers, two of them infants, and 12 crew members, the airline said.
The passengers are of 13 nationalities, the airline said.
At the time of its disappearance, the plane was carrying about 7.5 hours of fuel, Sharuji said.
"Malaysia Airlines is currently working with the authorities who have activated their Search and Rescue team to locate the aircraft," the statement said. The public can call +603 7884 1234 for further information.
Efforts to contact the plane were fruitless.
"We deeply regret that we have lost all contacts" with the jet, said CEO Ahmad Juahari Yahya in a statement.
The airline said in a statement that its representatives were contacting the relatives of those aboard. "Focus of the airline is to work with the emergency responders and authorities and mobilize its full support," it said.
China's state-run Xinhua News Agency said the flight lost contact and its radar signal as it was flying over the Ho Chi Minh air traffic control area in Vietnam.
Xinhua also reported that Chinese aviation authorities had confirmed that 160 Chinese nationals were aboard the plane, which was lost from radar in airspace controlled by Vietnam.
China's embassy in Malaysia has formed an emergency team headed by the Chinese ambassador to deal with the incident, it said.
"We're closely monitoring reports on Malaysia flight MH370," Boeing said in a tweet. "Our thoughts are with everyone on board."
"It doesn't sound very good," retired American Airlines Capt. Jim Tilmon told CNN's "AC360." He noted that the route is mostly overland, which means that there would be plenty of antennae, radar and radios to contact the plane.
"I've been trying to come up with every scenario that I could just to explain this away, but I haven't been very successful."
He said the plane is "about as sophisticated as any commercial airplane could possibly be," with an excellent safety record.
"The lack of communications suggests to me that something most unfortunate has happened," said Mary Schiavo, former inspector general of the U.S. Department of Transportation, in an interview with CNN International. "But that, of course, does not mean that there are not many persons that need to be rescued and secured. There's still a very urgent need to find that plane and to render aid."
There is one recent blemish for the Boeing jet: An Asiana Airlines Boeing 777 carrying 291 passengers struck a seawall at San Francisco International Airport in July 2013, killing three people and wounding dozens more.
Malaysia Airlines operates in Southeast Asia, East Asia, South Asia, the Middle East and on the route between Europe and Australasia.
It has 15 of the Boeing 777-200 planes in its fleet, CNN's Richard Quest reported.
Part of the company is in the private sector, but the government owns most of it.
Malayan Airways Limited began flying in 1937 as an air service between Penang and Singapore. A decade later, it began flying commercially as the national airline.
In 1963, when Malaysia was formed, the airline was renamed Malaysian Airlines Limited.
Within 20 years, it had grown from a single aircraft operator into a company with 2,400 employees and a fleet operator.
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