Story highlights The couple thought the book would stop the bullet

Pedro Ruiz III died from a single gun shot wound to the chest

(CNN) A Minnesota woman killed her boyfriend Monday by shooting at a book he was holding over his chest, in a YouTube video stunt gone wrong. Monalisa Perez,19, was attempting to make a viral video with boyfriend Pedro Ruiz III, 22, to post to their YouTube account, according to a Norman County Sheriff's Department arrest report.

Perez, who is seven months pregnant, called 911 on Monday evening, saying she had accidentally shot her boyfriend in the chest while they were making a video, according to the arrest report.

Monalisa Perez, 19, has been charged with second degree manslaughter.

She has been charged with second degree manslaughter. CNN has not been able to reach the public defender assigned to Perez for comment.

"They were in love. They loved each other. It was just a prank gone wrong," Ruiz's aunt, Claudia Ruiz, told CNN affiliate KVLY . "It shouldn't have happened like this. It shouldn't have happened at all." The couple had one child and were expecting their second together, his aunt told the news station.

He thought the book would stop the bullet

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