SANTA CLARITA, Calif. -- A 16-year-old Saugus High School student who walked into the campus quad Thursday and shot five classmates before turning the gun on himself died Friday at a hospital.
Nathaniel Tennosuke Berhow, a junior at Saugus High, died at 3:32 p.m. Friday, according to the sheriff's department. Sheriff's officials said his mother was with him when he died.
Meanwhile, investigators remained stymied in their search for a motive that prompted the shooting, which occurred shortly before 7:40 a.m. Thursday on the campus at 21900 Centurian Way.
"No motive or rationale has yet been established for the subject's assault," Sheriff's Capt. Kent Wegener said Friday.
All schools in the William S. Hart Union High School District were closed Friday "out of respect for the victims and their families," Deputy Superintendent Mike Kuhlman said. Instead, school district counselors were made available to students, parents and residents throughout the day at Grace Baptist Church in Santa Clarita.
As of late Friday, it was still unclear if the campuses would reopen Monday.
The coroner's office on Friday identified the two students killed in the shooting as Gracie Anne Muehlberger, 15, and Dominic Blackwell, 14.
"Our vivacious, funny, loyal, light of our lives, Cinderella, the daughter we always dreamed to have, fiercely strong and lover of all things fashionable -- was our best friend," Muehlberger's parents wrote in a statement on a GoFundMe page established on behalf of the family. "She is going to be missed more than words will ever be able to express.
"We deeply appreciate the outpouring of love and support from family, friends, colleagues, our church and the whole Santa Clarita and national communities. We are grieving and navigating this pain moment by moment. ... We will love you always Sweetpea!"
A friend and former youth football teammate of Blackwell posted a football team photo on Twitter and wrote, "Today a lil guy with a big heart lost his life in the Saugus shooting. He was always smiling making people laugh always positive. He was the sweetest kid ever and such a good kid. We need more people like you."
A 14-year-old boy wounded in the shooting was treated and released Thursday at Henry Mayo Hospital in Valencia. Two girls, aged 14 and 15, remained hospitalized Friday at Providence Holy Cross Medical Center in Mission Hills. Doctors said they were both recovering and could be released in the coming days.
Doctors said the 14-year-old was shot in a shoulder and abdomen and was in stable condition and "doing well." The 15-year-old girl had a single bullet wound that entered below her belly button and lodged in her left hip. Doctors performed surgery and were able to remove the bullet, officials said.
Gov. Gavin Newsom visited the injured students at Providence Holy Cross Medical Center on Thursday.
"A remarkable experience, being with 14-, 15-year-old survivors, that are consoling you, not the other way around," Newsom told Fox11. "They had this remarkable resilience, smiles on their face, one just coming out of surgery, the other one with two gunshot wounds and just remarkably blessed that they are alive, their families with them."
Newsom called the spirit of the wounded students "amazing."
Sheriff's officials said Berhow carried out Thursday's shooting on his 16th birthday. According to Wegener, campus security cameras captured footage showing Berhow walking into the campus quad, pulling a semiautomatic .45-caliber pistol out of his backpack and opening fire -- shooting five people then shooting himself in the head. The entire shooting took 16 seconds, Wegener said.
Deputies responding to 911 calls about a shooting found six people suffering from gunshot wounds in the campus quad. The handgun was recovered at the scene -- all of its bullets having been fired.
Wegener said the shooting appeared to be completely random, with the gunman firing at anyone in his vicinity. Wegener and Sheriff Alex Villanueva both reiterated Friday there appeared to be no discernable link between the shooter and the victims, other than they were students at Saugus High School.
Villanueva said the gunman didn't appear to have "any interaction with anyone" prior to the shooting. He was standing by himself, then walked to the center of the quad and opened fire, the sheriff said.
Paul Delacourt, assistant director in charge of the FBI's Los Angeles field office, said there was no early indication the suspect "was acting on behalf of any group or ideology."
Officials also said there is no history of the teen being bullied.
Wegener said investigators have not found a manifesto, diary, suicide note or any other writings indicating a motive.
Villanueva noted that three off-duty law enforcement officers -- one with the sheriff's department and officers from Inglewood and Los Angeles -- were the first people on scene because they have relatives who attend the school.
After learning the gunman's name by interviewing eyewitnesses and reviewing the surveillance video, deputies went to Berhow's family's home in the 22900 block of Sycamore Creek Drive and conducted an initial search to ensure there were no additional victims there, but none were found.
Villanueva said Friday investigators have identified six firearms that were registered to the suspect's late father, and all of those weapons have been accounted for -- but the gun used by Berhow in Thursday's shooting was not one of them, he said.
The sheriff said there were several firearms recovered from the house that "were not the ones registered to the father. Some of these firearms were not registered at all."
"We're going to have to go through and finish the investigation to account for all of the firearms and match them up with a source and the relationship with the weapon that we recovered at the scene," he said.
A cross-country teammate of the gunman said he was shocked the teen could be capable of such a violent act.
"He was the nicest person. ... I don't know why he would ever do this, especially on his birthday," the teammate told Fox11.
Neighbors told reporters the family was mostly quiet, noting that the teen's father had died two years ago, possibly from a heart attack. One neighbor said the father had struggled with substance abuse for years but was in recovery and building a relationship with his son when he died.
Wegener initially said an Instagram account attributed to the suspect included a post Wednesday night saying, "Saugus have fun at school tomorrow." However, officials with Instagram's parent company, Facebook, have since confirmed the account did not actually belong to the shooter and has since been disabled for violating the social-media site's policies.
Prayer vigils were held Thursday night at Grace Baptist Church and St. Stephen's Episcopal Church, both in Santa Clarita.
A community vigil is being planned at 7 p.m. Sunday at Santa Clarita's Central Park.