The boy's mother, Sujey Annel Cruz Cazarez, was grief-stricken in the living room.
"Why did they kill him? Why?" she said.
At 3 p.m., two sheriff's deputies patrolling in the area of Moorland and West Robles avenues observed Lopez walking with what sheriff's officials said appeared to be some type of rifle.
The deputies called for backup and repeatedly ordered the boy to drop the rifle, Sheriff's Lt. Dennis O'Leary said in a news release.
At some point after the deputies told Lopez to drop the rifle, they fired several rounds from their handguns at the boy, who was hit multiple times, O'Leary said.
After telling Lopez to move away from the rifle, deputies approached the unresponsive teen as he lay on the ground and handcuffed him before administering first aid and calling for medical assistance, O'Leary said.
Lopez was later pronounced dead at the scene. Neither deputy was injured, said Sheriff's Lt. Steve Brown. Sheriff's officials did not release the names of the deputies Tuesday, but said both had been placed on administrative leave.
After securing the scene, deputies discovered the rifle the teen was carrying was a replica of an assault weapon, O'Leary said. Deputies also found a plastic handgun in the teen's waistband.
The shooting took place at the edge of a field. The area was cordoned off for hours with yellow police tape. An ambulance and numerous patrol cars from both the Santa Rosa Police Department and Sheriff's Office surrounded the area.
Moorland Avenue was initially closed from West Robles to Corby avenues.
Neither the Sheriff's Office, nor the Santa Rosa Police Department, which is leading the investigation into the shooting, would release the boy's name Tuesday.
Eduardo Diaz, a friend of Rodrigo Lopez, said Tuesday evening that he received a phone call and learned the boy was dead.
Diaz said the boy's family lived near the corner of Todd Road and Moorland Avenue. The family said the boy recently attended Cook Middle School but had transferred to another school.
Moorland Avenue was blocked at Todd Road late Tuesday night.
At a little after 9 p.m., a police investigator's SUV pulled up to the family's home, a mobile home located on a property that has at least two other homes.
The boy's mother, distraught and in tears, came out of the SUV accompanied by someone who appeared to be a family member.
She walked back to her home escorted by police investigators. Neighbors said she had been taken to identify the body of her son.
Two law enforcement chaplains arrived soon afterward. The mother's cries could be heard from the dark driveway as the chaplains walked back to the residence in the rear of the property.
It was unclear Tuesday whether the weapon recovered at the scene was an operational pellet or BB gun. Lopez's family called the gun a "toy," but the Sheriff's Department's news release called it only a "replica" of an assault rifle.
There are dozens of Airsoft guns on the market designed to look like real assault rifles but are electric and fire plastic, nonlethal projectiles similar to BBs.
The gun recovered at the scene closely resembled an AK-47 style rifle, a replica of which can be purchased online for as little as $34.99 for a plastic version or more than $200 for ones with real metal and wood.