Investigators are treating this as a possible kidnapping.
Trains whizzed by the Ortiz house from the other side of Westmoreland Avenue, while Luis Ortiz's father stood at the front gate, as if he were waiting for his son to suddenly appear.
He just seems like a nice young man getting ready to graduate from high school," said Lt. Ray Lunny from San Mateo County Sheriff's Department.
Lt. Lunny said the missing 17-year-old called 911 from his cell phone around 9:15 p.m. on Tuesday night, as he babysat his two young brothers.
Lunny says the call was garbled but it sounded like intruders were in the house.
"We responded as if there is possibly two gunmen in there," said Lt. Lunny.
All police found were Luis' six and 9-year-old brothers in the house alone.
The children told investigators their brother thought he heard suspicious noises in the backyard.
They said he told them to stay in the bedroom while he investigated. The family says that was the last time the two youngsters saw Luis.
Investigators found speckles of blood on the glass door that leads to the yard and more blood on Luis' broken cell phone that was also found in the yard.
The missing teenager is a senior at Woodside High School. They say Luis was never in trouble.
"He's not in gangs; he's really a nice boy. He's been trying to graduate this year," said Luis Ortiz's aunt Guillermina Ortiz.
"No reason why anyone would want to kidnap him?" asked ABC7's Vic Lee.
"No, there is no reason," said Ortiz.
Police say they haven't ruled anything out.
We're treating this as a possible abduction. We're hoping that's not the case," said Lt. Lunny.