Sources claim that a second Russian Su-34 bomber was shot down by an F-16 of the Ukrainian Air Force.

Russian milbloggers report a mysterious aircraft downing, speculating Ukrainian F-16 involvement–potentially the second such incident since 12 October.
Defence Blog and Militarnyi, citing Russian military blogs, reported that a Russian Su-34 bomber-fighter was downed in mysterious circumstances early on 1 November. This is the second such loss to occur in recent weeks.
The Russian and Ukrainian authorities have not confirmed or denied the details of the incident. However, some unofficial Russian sources attribute it to a fight with a Ukrainian F-16. Russian Sukhoi Su-34 Fullbacks are used as tactical bombers that target Ukrainian positions in the front and border zones. These aircraft are often lost due to Ukrainian air defenses and technical problems, as well as crew errors.