A young boy lays a teddy bear outside the Dutch Embassy in Kiev, Ukraine, on July 20. / Dave Hunt, European Pressphoto Agency
Corrections & Clarifications: A previous version misidentified the Malaysian Minister of Transport, Liow Tiong Lai.
Following the Malaysia Airlines Flight MH17 crash Thursday - which killed all 298 on board - many questions still remain.
USA TODAY Network lists what we know now about the downed plane as the countries seek answers:
What challenges are investigators facing at the crash site?
Rebels reportedly forced investigators to hand over the remains of victims on Sunday and denied them access to the crash site. As many as 100 bodies remained unaccounted for.
"Malaysia is very concerned that the sanctity of the crash site has been severely compromised," Malaysian Minister of Transport, Liow Tiong Lai, said in a statement from Ukraine, where he has led a team of 133 investigators from his country.
Ukraine and Russian-backed separatists agreed Saturday to set up a security zone around the crash site of the Malaysia Airlines jet to allow the orderly removal of the bodies.
An international delegation visited the crash site Friday evening but was only allowed a superficial visit to see one small portion.
Who was on board Flight 17?
The jetliner was carrying 298 people. The victims came from 11 countries.
The victims include 193 Dutch (including one dual Netherlands/U.S. citizen), 43 Malaysians (including 15 crewmembers and two infants), 27 Australians, 12 Indonesians (including one infant), 10 Britons (including one dual U.K./S. Africa citizen), four Germans, four Belgians, three Filipinos, one Canadian and one New Zealander, according to the full flight manifest released by Malaysia Airlines on Saturday.
Malaysia Airlines and foreign embassies have "made every effort to establish contact with the next-of-kin" of the dead but still are unable to "identify many more family members," the airline said in a statement.
Where are the black boxes?
Rebel leader Alexander Borodai said the separatists recovered the black boxes from the flight and will hand them over to the International Civil Aviation Organization.
What kind of missile shot down the plane?
U.S. officials say it was a SA-11 surface-to-air missile that downed the Boeing 777. It is also known as a Buk, which was first built by the Soviet Union and is capable of shooting down jets traveling up to 70,000 feet.
Who took down the jetliner?
The latest U.S. intelligence assessment suggests that more than one missile system was provided to the separatists by the Russians in the past week or so, a U.S. official said Saturday, according to media reports. The official said it's not entirely clear whether the separatists just received the missile systems or whether they had them for a short time and only in recent days were trained or able to operate them.
The Pentagon said Friday that it is unlikely that pro-Russia separatists in eastern Ukraine could obtain or operate the sophisticated missile system allegedly used to shoot down the Malaysia Airlines plane without Russian help.
Ukraine's government says the jetliner was shot down by a Russian aircraft.
Where was the airliner headed?
The Malaysian airliner was en route from Amsterdam to Kuala Lumpur with 283 passengers and 15 crewmembers when it crashed into rebel-held territory in eastern Ukraine.
Follow @jessicadurando on Twitter
Read the original story: Malaysia Airlines Flight 17: What we know today