Last Updated Sep 9, 2015 5:40 PM EDT
SOUTH LOS ANGELES -- Three young brothers were found stabbed to death inside a vehicle parked outside a South Los Angeles elementary school, while a man suspected to be their father was in critical condition, police said.
The children were discovered Wednesday morning in south Los Angeles, reports CBS Los Angeles. Paramedics were called around 7 a.m. to the scene across the street from an elementary school.
"These are horrific incidents," Los Angeles Police Chief Charlie Beck said. "These are incidents that have scarred not only a community but the first responders that have to handle them."
The three boys did not attend the elementary school next to the crime scene, Beck said, but they are enrolled in the Los Angeles Unified School District.
When police arrived they discovered four victims in a silver Nissan parked along the curb, according to Brian Humphrey of the Los Angeles Fire Department.
Police say they found a knife inside the car.
John Sorrentino, whose furniture store is next to the crime scene, said he was the one who first spotted the bloody scene and called 911.
"I saw this man behind the steering wheel covered in blood," he said. "I got a little bit closer, and I saw a young child in the back seat and his eyes were half open and he was covered in blood. He was staring out, just in space. It's still etched in my mind."
Sorrentino said he then saw another boy bent over a seat, and in the back, a leg of the third boy lying upright. That's when he ran inside his store and called 911.
Police tell CBS LA they have a suspect in custody, but would not elaborate.
Beck said the boys' mother is deceased and that their stepmother was safe and being interviewed by detectives.
The deaths come as homicides are on the rise in Los Angeles. In August, 39 killings drove a year-to-date uptick in murders in the nation's second-largest city, according to police statistics. The 39 killings in August are compared with 22 the previous month and 19 last August.
Daniel Avalos, who works for Sorrentino and has five kids between the ages of 3 and 12, said he saw paramedics pulling the man out of the car and one of the children still in the back.
"We're in South-Central, so stuff like that kind of happens around here. But the fact that it's children - that's heart-wrenching," Avalos said. "It's hard to think about."