Reuters quoting Interfax reports that it was brought down by a surface to air missile. https://twitter.com/Reuters/status/489795394411712513
Edit: Thanks great replies!
The US shot down an Iranian airliner in 1988: http://en.wikipedia.org/wiki/Iran_Air_Flight_655
And the Russians shot down a Korean airliner in 1983: http://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007
(The only one I've heard of before was Iran Air Flight 655)
Some examples (in no particular ordering):
https://en.wikipedia.org/wiki/Iran_Air_Flight_655
https://en.wikipedia.org/wiki/Libyan_Arab_Airlines_Flight_114
https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_902 (air-to-air, not ground-to-air missile)
https://en.wikipedia.org/wiki/Air_Rhodesia_Flight_825
https://en.wikipedia.org/wiki/Air_Rhodesia_Flight_827
https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007 (air-to-air, not ground-to-air missile)
https://en.wikipedia.org/wiki/1983_TAAG_Angola_Airlines_Boeing_737_crashAfter more than 30 years we still don't know for sure what happened...
It's now widely accepted that the Itavia 870 was downed by a NATO plane, likely French, likely engaged in some sort of anti-Lybic operation.
http://www.nytimes.com/2001/10/14/world/after-9-days-ukraine...