KUALA LUMPUR, Malaysia --U.S. intelligence officials believe a surface-to-air missile brought down the Malaysia Airlines jetliner that crashed in Ukraine.
Officials say 295 people are believed to be dead after Flight 17 crashed in the nation's eastern region near the Russian border on Thursday.
The jetliner, traveling from Amsterdam to Kuala Lumpur, was believed to be flying about 33,000 feet when airline officials say they lost contact with the Boeing 777.
At least one U.S. official says analysis now shows that the plane was brought down by a sophisticated missile, although it's unclear where it was fired from and who is responsible.
Experts say the pilot likely had no time to react.
"My guess is this came out of nowhere and there was absolutely no warning," said ABC News military consultant Stephen Ganyard.
On Thursday Malaysia's prime minister said the jetliner did not make any distress call before it went down in Ukraine, and that the flight route was declared safe by the International Civil Aviation Organization.
Prime Minister Najib Razak told reporters that Ukrainian authorities believe the Boeing 777, on its way from Amsterdam to Kuala Lumpur, was shot down.
He says that Malaysia, however, is unable to verify "the cause of this tragedy but we must, and we will, find out precisely what happened to this flight.
This scene is unfolding in an area where tensions between Ukraine, pro-Russian rebels, and the Kremlin have been escalating.
In the past week, Ukraine claimed Russia shot down two of its military planes. That's one factor behind President Barack Obama's increased sanctions against Russia, announced Wednesday.
The president on Thursday said that the U.S. will help with the crash investigation.
"The United States will offer any assistance we can to help determine what happened and why. And as a country, our thoughts and prayers are with all the families of the passengers, wherever they call home," he said.
This is another nightmare involving Malaysia Airlines, just more than four months after Flight 370 mysteriously disappeared.
Families are now waiting for information as investigators still make their way to the scene.
The the state department says they are still looking into reports that there may have been Americans onboard.
AIDS researchers on board Malaysian flight
Several passengers on board the Malaysian jetliner shot down over Ukraine were heading to an international AIDS conference in Australia.
Australian Foreign Affairs Minister Julie Bishop said Friday that several people on board the Boeing 777 were en route to Melbourne to attend next week's conference.
The International AIDS Society issued a statement expressing "sincere sadness" that several of its colleagues and friends were on board the plane.
Bishop says at least 27 Australians were on board. The aircraft was scheduled to continue flying to the western Australian city of Perth after stopping in Kuala Lumpur, Malaysia
Here's a breakdown of the nationalities of the passengers and crewmembers, according to ABC News -- 154 were Dutch, 38 were Malaysian (including 15 crewmembers, 27 were Australian, 11 were Indonesian, and six were British. Four people apiece were from Germany and Belgium, and at least four of the passengers were French. There were three Filipinos and one Canadian on board. The nationalities of 43 passengers remain unknown.
(The Associated Press contributed to this report)