A Malaysia Airlines flight carrying 227 passengers and 12 crew remains missing over the South China Sea, presumed crashed.
The airline on Saturday morning said teams from Malaysia, Vietnam and Singapore had been sent to scour a large area near its last known location. They failed to find evidence of any wreckage.
But a 12-mile oil slick reported between Malaysia and Vietnam could prove an early sign that the jet crashed into waters.
The sea search mission will continue overnight while the air mission will recommence at daylight, Malaysia Airlines said in a statement.
Earlier Saturday, Malaysian Prime Minister Najib Razak provided details about the search and rescue mission.
“Fifteen aircraft and nine ships are currently searching for the missing plane. Our priority now is to widen the search area and provide support to relatives of those missing," he said.
The Boeing 777-200ER flight from Kuala Lumpur to Beijing had been missing for hours when Vietnam's Tuoi Tre news quoted Admiral Ngo Van Phat as saying he had asked boats from an island off south Vietnam to rush to a potential crash site.
Malaysia Airlines had yet to confirm that the aircraft had crashed and the Admiral later clarified his remarks, saying he had been referring to the presumed crash site.
A crash, if confirmed, would mark the U.S.-built Boeing 777-200ER airliner's deadliest incident since entering service 19 years ago.
Malaysia's flag carrier said flight MH370 disappeared, without giving a distress signal, at 2:40 am local time on Saturday, about two hours after leaving Kuala Lumpur International Airport.
It had been due to arrive in Beijing at 6:30 am local time on Saturday.
The flight was carrying 153 people from China or Taiwan including one infant, 38 Malaysians, seven Indonesians, five Indians and six Australians among the 227 passengers, the airline said on Saturday.
There were also three U.S. citizens including an infant, four from France, two passengers each from New Zealand, Ukraine and Canada. There were also two infants and twelve crew members on the flight.
In a twist to the unfolding drama, the passenger manifest issued by the airline included the names of two Europeans, who, according to their foreign ministries, were not in fact on the plane. Their passports had previously been reported as lost or stolen.
But there are no indications of sabotage nor claims of a terrorist attack. U.S. and European security officials said there could be other explanations for the use of stolen passports.
"We deeply regret that we have lost all contacts with flight MH370 which departed Kuala Lumpur at 12.41 am earlier this morning bound for Beijing," Ahmad Jauhari Yahya, Malaysia Airlines group chief executive officer, said in a statement.
The airline's Kuala Lumpur-Beijing route passes roughly over the Indochinese peninsula.The statement said the carrier was working with authorities, who had launched an effort to locate the aircraft.
Al Jazeera's Rob McBride, reporting from Beijing Airport, where the plane had been due to land, said there had been little information from the authorities.
"It seems the airline and the authorities are as much in the dark as everyone else," he said. "We are getting reports from all sides that (the different aviation authorities) are collaborating as much as possible on the search."
Ross Aimer, a former pilot with United Airlines, told Al Jazeera it was highly unusual that air traffic control would lose contact with an aircraft without communication from the crew.
"The fact that there was absolutely no distress signal is very disturbing. This is almost unprecedented that we lose an aircraft in such a way … In that area of the world, over Vietnam, there is sporadic radar coverage to begin with," he said.
He said the Chinese authorities would have communicated something to the outside world if it was a hijacking case. A report by China's Xinhua news agency said contact was lost with the plane while it was near Vietnamese airspace.
Malaysia Airways said the situation in Beijing is being monitored closely. It deployed a team of caregivers and volunteers to assist the family members of the passengers in China. "Our sole priority now is to provide all assistance to the families of the passengers and our staff," according to a company statement.
"Immediate families of passengers are advised to gather at Kuala Lumpur. Travel arrangements and expenses will be borne by Malaysia Airlines. Once the whereabouts of the aircraft (are) determined, Malaysia Airlines will fly members of the family to the location."
Al Jazeera and wire services