Some cities in Syria are battered by hundreds of airstrikes every day.

And when those bombs hit — at least when they fall in opposition areas — unarmed volunteers known as the White Helmets are the first on the scene digging through rubble and searching for survivors.

Officially called the Syrian Civil Defense, the group is the subject of a new documentary premiering on Netflix on Friday.

The 40-minute documentary focuses on three volunteers: a builder, a blacksmith and a tailor. It also checks in with a toddler who, as an infant, was saved by White Helmet Khaled Omar Harah. Harah was the face of the group before he was killed by an airstrike last month.

The White Helmets say they’ve saved about 60,000 people in the course of the five-year civil war.

The cost? More than 140 of their own volunteers’ lives.

"We thought we had an idea of what these men and women went through," said Orlando von Einsiedel, the film’s director. "We were definitely taken aback by just how horrendous the work they do is.”

Von Einsiedel never actually entered Syria. He relied on the White Helmets themselves to gather footage from the front lines, while his crew filmed interviews in Turkey.

The volunteers sometimes train in Turkey, which Von Einsiedel also captured in the documentary. He remembers the White Helmets checking their phones after training to find out the news of the day back in Syria.

“They’d be getting news of 200 bombs hitting one particular city in a day. For us, it was very emotional to go through that with them. But clearly they're going through an enormous amount more,” he said.

The White Helmets have been nominated for the 2016 Nobel Peace Prize, but the group is also criticized.

That's because they operate exclusively in opposition zones, although their charter states that volunteers are unarmed and neutral. Critics say The White Helmets have ties with jihadist groups, and point to video footage that appears to show volunteers celebrating with fighters carrying the flag of an al-Qaeda-linked rebel group.

Some dismiss the documentary as propaganda.

However, von Einsiedel and Joanna Natasegara, the film’s producer, say they believe they have the full story.

“In any war there's a lot of rumor, a lot of incidents that go around,” Natasegara said. “We're very comfortable that the White Helmets deal with their disciplinary processes correctly. We're comfortable with their charter, and we are really sure that their work is overwhelmingly for the good, that their work is humanitarian.”

From PRI's The World ©2016 PRI