The pair, locked in a duel for second place, came together on the final lap of the race, ending both their hopes of securing a medal.
Poland’s Krystyna Palka and Olena Pidhrushna of Ukraine took advantage to take silver and bronze respectively, with Norway's Tora Berger claiming gold ahead of the drama.
Yet neither Flatland nor Zaitseva pointed the finger of blame following the incident, even though Flatland did apologise immediately after the race.
”I don’t know what have happened," Norway's Flatland said. "We were racing side by side and suddenly I felt, I lost control of my ski. There has been a lot of ice, it was very steep. Skis were on the edge. I think those things happen: we both fell.
"I apologise, we were both fighting for a medal. It’s biathlon."
Russian Zaitseva said: "Flatland came to me after the race and she have apologised about the incident. She said that she is very sorry. I understand her and I don’t want to blame her.
"It was a situation that nothing can be done. This fall had deprived both us from the medals. What can I do? Fourth place is my final place now and that’s it."