Mass school shootings fill TV screens with bloody images, newspapers with heart-wrenching accounts from terrified students, and pose searching questions about the motives of the young killers.

But the movie "Beautiful Boy", opening in U.S. theaters on Friday, puts a rare spotlight on the anguished parents of a teen gunman.

Maria Bello and Michael Sheen star in the independent film as Kate and Bill, whose already fractured marriage is further tested when their only son goes on a rampage at his college before turning the gun on himself.

"Parents are regular people doing the best they can to raise a child," director and co-writer Shawn Ku told Reuters.

"But when something like this happens, they are so often forgotten, or worse, blamed. We thought it was worth showing their humanity," he added.

"Beautiful Boy" is the second movie this year on the topic of school shootings. "We Need to Talk About Kevin" -- based on Lionel Shriver's 2003 novel -- debuted at the Cannes film festival in May, starring Tilda Swinton as a woman trying to put her life back together in the wake of her son's killing spree. It is due for release later this year.

The two films follow the 1999 massacre at Columbine High School in Colorado, where two teens killed 12 students and a teacher before committing suicide, and the 2007 Virginia Tech shootings, where an undergraduate with mental health problems shot 32 people to death, then killed himself.

In "Beautiful Boy," the shootings happen off screen.

"Ultimately our story is about grief and love. The shooting is secondary," said Ku.

Kate and Bill are already sleeping in separate beds before the shooting occurs. Afterward, the media onslaught forces them to move in with relatives who have a young child of their own.

There the couple is forced to sleep in the same bed, while Kate dotes on the child, as if wanting to have a second chance at raising one.

"They blame themselves, they blame each other, they blame their marriage and the fact that they weren't happy role models. They blame the kids at school," said co-writer Michael Armbruster.

"We wanted them to struggle with that throughout the whole film, just like any parent would in real life," he added.

However the "why" of the crime is something that is never solved.

The movie has received strong reviews, particularly for the performances of Bello and Sheen. But the filmmakers realize they have a tough sell on their hands.

"We know that there is only a certain kind of person that's going to take the time to come see this film," said Ku. "Hopefully through word of mouth, others will too."

After all, said Ku, "No parent sets out to create a monster."