The Tribeca Film Festival opened Wednesday evening with The Five-Year Engagement, a crowd-pleasing comedy that brought stars Jason Segel and Emily Blunt to the red carpet.

Written by Segel and Nicholas Stoller, who also created Forgetting Sarah Marshall, the film is about "how an engagement can get in the way of a relationship," Stoller said.

Most of the program of 90 films selected for the festival, based in Lower Manhattan, focuses on independent productions. This edition will include 50 world premieres.

Among the films in competition is War Witch (Rebelle), Montreal director Kim Nguyen's tale about a 12-year-old African girl who is forced to gun down her parents and then driven to wage war as a child soldier.

Actress Emily Blunt attends the Tribeca Film Festival opening night premiere of The Five-Year Engagement Wednesday in New York. (Evan Agostini/Associated Press)

War Witch had its worldwide debut in February at the Berlin International Film Festival, where it was the first Canadian movie selected for competition in 12 years. Young star Rachel Mwanza won the best actress award in Berlin.

Nguyen and Mwanza promoted the film in Montreal Wednesday, ahead of its commercial release on Friday.

"It became more of a love story set in a war period, rather than a didactic film about child soldiers. The real heroes of those tragedies are the people who are involved in those conflicts," said Nguyen, who shot the film in the Congo.

Nguyen discovered lead actress Mwanza, just 14, through a documentary about people living on the streets of Kinshasa, he told CBC News. She'd never acted before, but the filmmaker said she comes across as fully genuine in the difficult role.

"She could go in all of these emotions, happiness as well as sadness. So, I just asked her and she said she just relates to things she lived in the past,” he said.

Mwanza said she thought back to the loss of her own parents and her life on the streets to conjure up emotions.

War Witch is competing in Tribeca's World Narrative Competition, against films such as:

• The First Winter, in which a group of Brooklyn hipsters try to survive in a remote country farmhouse with no heat and no electricity during the coldest winter on record.
• The Girl, starring Australian Abbie Cornish, about a single mother caught in a difficult situation after losing her job and custody of her son.
• Nancy, Please, about a man dealing with a sinister roommate.
• Postcards from the Zoo, an Indonesian film about a young woman raised at the zoo.

There is also a strong documentary lineup, beginning with The World Before Her by Canadian Nisha Pahuja, a former National Film Board of Canada filmmaker who also wrote and directed the Gemini Award-winning Diamond Road.

In The World Before Her, Pahuja turns her lens onto the situation of women in contemporary India, focusing on two women headed for the Miss India pageant as well as looking at a fundamentalist Hindu camp for girls.

The festival will return to bigger budget Hollywood fare for its closing night film, the superhero blockbuster The Avengers, screening on April 28.