The 16-year-old Southern California high school student who shot five of his classmates Thursday before turning the gun on himself has died, authorities said late Friday.

The Los Angeles County Sheriff's Office confirmed that Nathaniel Tennosuke Berhow passed away at 3:32 PT. His mother was present at the time, according to the sheriff's office statement.

Authorities say Berhow pulled a gun from his backpack Thursday at Saugus High School in the Los Angeles suburb of Santa Clarita, shot five students at random in an outdoor plaza and then shot himself in the head. The shooting, captured on surveillance video, took 16 seconds. Investigators told reporters earlier Friday they have not uncovered a motive for the shooting, despite undertaking more than 40 interviews.

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The attack killed 15-year-old Gracie Muehlberger and 14-year-old Dominic Blackwell. Two girls remain hospitalized but are expected to be released this weekend. Their names have not been released. A 14-year-old boy was treated and released from another hospital, authorities said.

Though police have not found a motive for Berhow's attack, they do believe it was premeditated. When Berhow's mother dropped him off at school, he had the pistol and a planned number of shots in his bag.

“You have the image of a loner, someone who is socially awkward, doesn’t get along, some violent tendencies, dark, brooding and online strange postings — stuff like that,” Los Angeles County Sheriff Alex Villanueva said. With this boy, investigators have found “nothing out of the ordinary. He’s a cookie-cutter kid that you could find anywhere.”

Authorities also said that no diary, manifesto, or suicide note had been found.

Blackwell was a part of the Saugus Junior ROTC program and previously played for a local pop warner league in Santa Clarita, according to Hometown Station,

"He was always smiling making people laugh, always positive, he was the sweetest kid ever and such a good kid," a teammate of Blackwell's said of him on Twitter. "We need more people like you long live dominic blackwell, [sic] love you."

Muehlberger had recently celebrated her 15th birthday. Her classmates described her as sweet and fun, a girl known and loved by virtually everyone, the Los Angeles Times reported.

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“My heart is killing me right now,” a person identified as Gracie’s brother posted to Twitter. “You are the best sister I could’ve asked for, I just know you’re my guardian angel now. I love you Gracie."