Malaysia's premier has expressed "shock" at reports a Malaysia Airlines flight may have been shot down over troubled eastern Ukraine as his nation reeled from another wrenching air tragedy just months after MH370 disappeared.
Tearful relatives began gathering at Kuala Lumpur's international airport in the early hours of Friday morning, many beside themselves with grief as they endured an agonising wait.
One woman, Akmar Mohd Noor, said her 67-year-old sister was among the 298 people on board Flight MH17, adding that she rushed to the airport as soon as she saw the news on television.
"She was coming back from Geneva to celebrate Hari Raya (Eid al-Fitr) with us for the first time in 30 years. Her son was supposed to come with her but he refused to come with her," she said between sobs.
"She called me just before she boarded the plane and said 'see you soon'."
The crash is a fresh blow to the flag carrier which, along with the Malaysian government, is still struggling to provide answers to the disappearance of flight MH370 on 8 March.
At a press conference early on Friday a sombre Malaysian Prime Minister Najib Razak, dressed in black, said the world was "united in grief" over the disaster.
"This is a tragic day, in what has already been a tragic year, for Malaysia," he said.
As questions were raised over why the passenger jet was flying over an active war zone, Najib said international air authorities had deemed the flight path safe.
"The aircraft's flight route was declared safe by the International Civil Aviation Organisation. And (the) International Air Transportation Association has stated that the airspace the aircraft was traversing was not subject to restrictions," he said.
Najib added that a team of disaster response specialists had been dispatched to Kiev and that authorities in Ukraine had agreed to try and establish "a humanitarian corridor to the crash site".
US and Ukrainian officials believe the Boeing 777, which Malaysia Airlines said was carrying 280 passengers and 15 crew, was shot down by a surface-to-air-missile.
The stricken flight had been expected in the Malaysian capital at 6.10am (0800) on Friday.
Some relatives at Kuala Lumpur's international airport expressed anger that they still had not been briefed by Malaysia Airlines officials.
"We have been waiting here for four hours… Where is MAS (Malaysia Airlines)?" an ethnic Chinese with relatives on board the flight said, declining to give his name.
Another ethnic Indian man who said his sister, brother-in-law and their two-year-old baby were believed to be on the flight said: "We just want to have the name list from MAS."
The crash comes just months after Malaysia's Flight MH370 disappeared on March 8 with 239 on board. That plane diverted from its Kuala Lumpur to Beijing flight path and its fate remains a mystery despite a massive aerial and underwater search.
No trace of that plane has yet been found.
Malaysian Transport Minister Liow Tiong Lai, who was on a China visit, tweeted: "I'm taking the first flight back from Beijing to be on top of #MH17. Pray and hope please."
Liow took over last month in a cabinet shuffle from then-acting transport minister Hishammuddin Hussein, who gained world notoriety with his daily briefings on the MH370 saga. Hishammuddin remains defence minister.
During his press conference, Najib said it was too early to tell whether MH17 had been down by a missile.
But he added: "If it transpires that the plane was indeed shot down, we insist that the perpetrators must swiftly be brought to justice."