Students say the Pledge of Allegiance as thousands gather at a candlelight vigil for several students killed in the Saugus High School shooting in Central Park, Sunday, Nov. 17, 2019, in Santa Clarita, Calif. Detectives were searching for a motive for the killings carried out by Nathaniel Tennosuke Berhow on Thursday, his 16th birthday. (Carolyn Cole/Los Angeles Times via AP)

SANTA CLARITA, Calif. (AP) — Thousands of people held a candlelight vigil to remember two students shot and killed by a classmate at his Southern California high school as investigators try to determine what prompted the deadly attack that left three other teens wounded.

The brother of one of the two students killed told people at the vigil Sunday in Central Park that his sister 15-year-old Gracie Anne Muehlberger “was the best sister ever.”

“You always put a smile on my face,” he added.

Riley Muehlberger shared fond memories of his sister’s birthday party and how she would talk to him about her life at school.

“I watched you grow up more and more every day. You said you looked up to me when I graduated from Saugus,” he said.

Angie Davidson, an aunt of 14-year-old Dominic Blackwell, said his death has devastated the family. Davidson was surrounded by other family members, several who were crying, as she spoke.

“He’s gone forever. We are broken,” Davidson said. “Please remember the two precious lives that we lost.”

Dominic Blackwell was an ROTC student at Saugus. Two of his fellow ROTC cadets remembered him as a fun-loving and helpful classmate.

Saugus Principal Vince Perry told the crowd at the vigil that the event was a moment to grieve.

“We are here to grieve the loss of two teenagers, two friends, two students, two siblings and two children,” he said

Joann Garcia said she came to the vigil at Central Park shaken but determined to help the community heal from the shooting at Saugus High School.

“It’s very hard. We thought that this would never happen here. It has affected everybody,” she said. “We are all uniting.”

Santa Clarita Mayor Marsha McLean touched on the theme of the vigil in her remarks. “Tonight and every day we are Saugus strong,” she said.

Saugus High School will remain closed until Dec. 2, but counselors will be available to help students cope with their grief, said school district officials in the Los Angeles suburb of Santa Clarita.

Detectives were searching for a motive for the killings carried out by Nathaniel Tennosuke Berhow on Thursday, his 16th birthday. The teen pulled a .45-caliber handgun from his backpack and shot five students at random before shooting himself in the head. He died the next day.

A wounded 14-year-old girl was released from the hospital late Friday. A 15-year-old girl remained hospitalized in good condition. A 14-year-old boy was treated and released Thursday.

Berhow had shown no signs of violence and didn’t appear to be linked to any ideology, authorities said.

After more than 40 interviews and a search of his home, authorities still were in the dark, Capt. Kent Wegener of the Sheriff’s Department’s homicide unit said at a news conference Friday.

"We did not find any manifesto, any diary that spelled it out, any suicide note or any writings," he said.

Additional law enforcement will be posted Monday at schools in the Santa Clarita area.

This undated photo provided by the Muehlberger family shows Gracie Anne Muehlberger, 15. She is one of two students who died when Nathaniel Tennosuke Berhow opened fire at Saugus High School in Santa Clarita, Calif., Thursday, Nov. 14, 2019. Berhow, 16, planned the attack at the Southern California high school, but investigators were so far unable to find out why he brought a gun to campus and opened fire, authorities said Friday. (Muehlberger family via AP)
Parent Mirna Herrera kneels with her daughters Liliana, 15, and Alexandra, 16 at the Central Park memorial for the Saugus High School victims in Santa Clarita, Calif., Friday, Nov. 15, 2019. Investigators said Friday they have yet to find a diary, manifesto or note that would explain why a boy killed two students outside his Southern California high school on his 16th birthday. (AP Photo/Damian Dovarganes)
Emily Boyle, a senior at Valencia High School brings flowers at a memorial near Saugus High School in Santa Clarita, Calif., Friday, Nov. 15, 2019. A homicide official says that investigators did not find a diary, manifesto or note belonging to the boy who killed two people outside his Southern California high school on his 16th birthday. Officials held a press conference Friday outside of the police station Santa Clarita. No motive or rationale has been established yet in the Thursday morning shooting at Saugus High School in the Los Angeles suburb of Santa Clarita. (AP Photo/Damian Dovarganes)
A Los Angeles Sheriff Sheriff's vehicle patrols the surroundings of the Saugus High School in Santa Clarita, Calif., Friday, Nov. 15, 2019. Investigators said Friday they have yet to find a diary, manifesto or note that would explain why a boy killed two students outside the Southern California high school on his 16th birthday. (AP Photo/Damian Dovarganes)
Deputy James Callahan, at podium, takes questions from the media at a news conference at the station Santa Clarita, Calif., Friday, Nov. 15, 2019. Callahan works as a school resource officer at Saugus High School, was on the scene in the aftermath of the shooting, (AP Photo/Damian Dovarganes)
Santa Clarita Mayor Marsha McLean, far left, Los Angeles Sheriff Sheriff Alex Villanueva, left, Detective Daniel Finn, at podium, and Deputy James Callahan, far right, take questions from the media at a news conference at the station Santa Clarita, Calif., Friday, Nov. 15, 2019. (AP Photo/Damian Dovarganes)
Doctors at Providence Holy Cross Hospital in Mission Hills tell reporters they treated a 15-year-old girl and a 14-year-old girl after Thursday's shooting at Saugus High School in Santa Clarita, during a news conference Friday, Nov. 15, 2019 in Los Angeles.  The suspected gunman shot five students, seemingly at random, and then shot himself in the head and remains in critical condition Friday.  (AP Photo/Damian Dovarganes)
Los Angeles Sheriff Sheriff Alex Villanueva expresses his condolences for the victims of the shooting at Saugus High School at a news conference at the station Santa Clarita, Calif., Friday, Nov. 15, 2019. (AP Photo/Damian Dovarganes)
Hannah Schooping-Gutierrez, center, a student at Saugus High School, is comforted by her boyfriend Declan Sheridan, at right, a student at nearby Valencia High School during a vigil at Central Park in the aftermath of a shooting at Saugus Thursday, Nov. 14, 2019, in Santa Clarita, Calif. (AP Photo/Marcio Jose Sanchez)
Students embrace during a vigil at Central Park in the aftermath of a shooting at Saugus High School Thursday, Nov. 14, 2019, in Santa Clarita, Calif. Los Angeles County sheriff’s officials say a 16-year-old student shot five classmates and then himself in a quad area of Saugus High School Thursday morning. (AP Photo/Marcio Jose Sanchez)
People hug each other during a vigil for the Saugus High School shooting victims at Central Park, Thursday, Nov. 14, 2019, in Santa Clarita, Calif. Los Angeles County sheriff’s officials say a 16-year-old student shot several classmates and then himself in a quad area of Saugus High School Thursday morning. (Hans Gutknecht/The Orange County Register/SCNG via AP)
Jessica Dumont, a former student at Saugus High School, places balloons on a makeshift memorial at Central Park in honor of the victims of a shooting at the high school Thursday, Nov. 14, 2019, in Santa Clarita, Calif. Los Angeles County sheriff’s officials say a 16-year-old student shot several classmates and then himself in a quad area of Saugus High School Thursday morning. (AP Photo/Marcio Jose Sanchez)
Members of Saugus High School's Air Force JUNIOR ROTC unit hold a moment of silence in memory of the victims of a shooting at the school earlier in the day Thursday, Nov. 14, 2019, in Santa Clarita, Calif. Los Angeles County sheriff’s officials say a 16-year-old student shot five classmates and then himself in a quad area of Saugus High School Thursday morning. (AP Photo/Marcio Jose Sanchez)
Flowers are placed in front of Saugus High School in the aftermath of a shooting on Thursday, Nov. 14, 2019, in Santa Clarita, Calif. (AP Photo/Marcio Jose Sanchez)
Ella Cabigting is embraced by her father Emerson as they reunite following a shooting at Saugus High School that injured several people, Thursday, Nov. 14, 2019, in Santa Clarita, Calif. (AP Photo/Ringo H.W. Chiu)
Emergency personnel remove an injured person following a shooting at Saugus High School, Thursday, Nov. 14, 2015 in Santa Clarita, Calif. (David Crane/The Orange County Register via AP)
Medical personnel load an injured person into an ambulance outside Saugus High School in Santa Clarita, Calif., after a student gunman opened fire at the school on Thursday, Nov. 14, 2015. (Rick McClure via AP)
Students are escorted out of Saugus High School after reports of a shooting on Thursday, Nov. 14, 2019, in Santa Clarita, Calif. (AP Photo/Marcio Jose Sanchez)