"Nobody should die for a misunderstanding, especially not a young boy who hasn't even started his life. It's just really sad knowing that," Viviany Diaz Agirra Torres, 17, told The Associated Press.
The FBI is conducting its own investigation into Lopez's death, the Sonoma County Sheriff's Office said Saturday.
"The Sheriff will cooperate fully with the FBI and welcomes their participation," the Sheriff's office said in a statement. "The Sheriff also wants to express his thankfulness to the community for how peaceful and respectful the memorials and protests have been in the aftermath of this incident."
Andy Lopez has been described as popular, smart and capable by school administrators. His father, Rodrigo Lopez, told the Press Democrat that the pellet gun belonged to one of his son's friends.
"I told him what I tell him every day," he said of his last encounter with his son. "Behave yourself."