(CNN) The two teens killed when a fellow student opened fire at their Southern California high school this week have been identified.

Grace Anne Muehlberger, 15, and Dominic Blackwell, 14, died at the hospital, authorities said. Three other teens were wounded and are expected to survive.

The gunman randomly shot students after taking out a .45-caliber pistol from his backpack at the quad area in Saugus High School in Santa Clarita. After targeting his schoolmates Thursday, he used the last bullet to shoot himself the same day he turned 16. He died at the hospital Friday, and his motive remains a mystery, the Los Angeles County Sheriff's Department said.

Chloe Rogers said her friend Muehlberger had a bubbly personality and knew how to make her laugh.

Grace Anne Muehlberger, 15, was one of two students killed in the Saugus High School shooting.

"We would always share our silly jokes with each other, make Vine references, and laugh forever. Her laugh was a laugh that would make you laugh harder," Rogers said. "She always had something kind to say and knew how to hype up her friends. I love her so much and going to school knowing she won't come up to me at random times to talk is heartbreaking."

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