In a Mariupol maternity hospital, doctors delivered a baby via cesarean section. But for a long time, the room was silent.

Finally, the baby cried. A sign of life in a hospital room that had mostly known death since the start of the war with Russia.

“Then everyone started to cry,” Ukrainian journalist Mstyslav Chernov told Boston Public Radio on Thursday. Chernov is a filmmaker and photographer whose new film “20 Days in Mariupol” documented this scene and many others during the early days of the Russian invasion of Ukraine.

The film, produced in collaboration with FRONTLINE and the Associated Press, debuts this Friday in New York City. On Monday, July 17, a special screening and Q&A at the Coolidge Corner Theater in Brookline will be moderated by GBH president and CEO Susan Goldberg.

Before the Russian siege started on Feb. 24, 2022, Chernov said he and his fellow journalists decided they would stay in the southeastern city to record the war.

“We knew how important Mariupol would be for Russia to try to take over because they’ve been trying this since 2014,” Chernov said. The team of journalists worked alongside doctors and firefighters working to save people from rubble. “How could we think about leaving? ... Everyone was dedicated to survival and to helping people next to them. We just did our job,” he said.

That job was to record violence and tragedies in real time. Having photos and videos is important to document potential war crimes. When there are no journalists, there’s a void in information, Chernov said. He cited the bombing of a theater in Mariupol, where close to 600 people were killed. “It took us months to ... try to reconstruct that event,” he said.

The journalists only left the city when they no longer had means to work. When the hospital was occupied by Russian troops and the Red Cross location bombed, they had no place to charge their equipment batteries.

The film shows the bodies of people in the streets and injured people in hospitals. Chernov has heard from viewers that his film is hard to watch — but that “these moments of hope are shining through.”

“Yes, it is hard, it is heartbreaking,” he said. “But there is hope there, and there is a resilience, a resistance of Ukrainian people who survive nevertheless, regardless of their indiscriminate violence that is happening to them.”

Hope comes from moments like the baby born in the middle of a war. Chernov said one of the doctors said to him that day, “We used to see only people dying in this hospital. So having a child born is just like a ray of light coming down from heaven to us.”

Yet what’s captured in the film is just a fraction of what Chernov and others witnessed in Mariupol and across Ukraine. “Mariupol is just a tiny fraction of what has happened to Ukraine. Other cities have been destroyed with the same tactics of burned land. ... I still have a lot of regrets for not being able to capture everything,” he said.

Aside from taking time to promote “20 Days in Mariupol,” he's been filming on the frontlines every day. “I can see so many things that just couldn’t be reported on — haven’t been reported on — because, well, because it’s just too overwhelming.”

The film will eventually be broadcast on PBS and available on streaming services. Chernov said his goal is for as many people to see the film as possible, including his daughters, whom he spends time away from while reporting on the front lines. “They are too little to understand right now what is going on. But someday they will ask me, and I will just show them this film,” he said.