A new documentary about the first days of the Russian invasion of Mariupol, Ukraine is premiering in Canada at the Hot Docs Film Festival in Toronto on Saturday.

Mstyslav Chernov, an Associated Press journalist and the director of , along with two colleagues captured graphic footage of civilian deaths, a maternity hospital bombing, and the beginnings of the war in the eastern Ukraine port city.

鈥淲e are Ukrainians and we are journalists. And we just felt that it was our duty to stay and to keep reporting as long as it was possible,鈥 Chernov told CTV鈥檚 Your Morning on Friday.

At the time, Chernov and his colleagues were the  in Mariupol.

The footage Chernov and The Associated Press journalists Vasilisa Stepanenko and Evgeniy Maloletka were able to gather and share reports and video of the invasion, including footage of a pregnant woman stretchered out of a bombed maternity hospital on a stretcher that was seen worldwide. Chernov believes their reporting had an impact on the international support and aid Ukraine received in the first days of the war.

In Russia, their footage was claimed as propaganda, Chernov told Your Morning, but 鈥渁s international journalists, we just [had] to keep filming鈥 And we did all of this not because Russia said that we're actors, we did this because it was important to keep showing what was happening to [the Ukrainian] people.鈥

Earlier this year Chernov and his colleagues won the Canadian Journalists for Free Expression for their reporting in Mariupol.

20 Days in Mariupol is playing at the in Toronto on Saturday at 2:45 p.m. EST. You can stream the film on the Hot Docs website from May 5 to May 9.