San Bruno, California (CNN) -- At first, residents thought it was an earthquake. Or maybe a big airplane had crashed. San Bruno, after all, is adjacent to the San Francisco airport.
They heard the booms. Then they saw the giant fireballs, some leaping 80 feet high. The flames were so hot, so intense, that the roar could be heard far away and the heat sucked up the air.
They did not know then that a gas line that had ruptured and exploded, triggering a fire that would leave their town in apocalyptic hues. They would only find out later what had happened. But in the middle of the chaos, they simply tried to survive.
Homes, lawns, cars -- everything burned. At least four people died. Many others gasped their way to hospitals, four of them fighting for their lives with excruciating third-degree burns.
Judy Serresseque felt her whole house shake as though a mighty quake was about to swallow northern California, her living room filled with an orange glow.
"When I went to my front door, I looked out and everything was just flames," said Serresseque, who fled with her husband. "The heat was intense, and you could hear it, you could hear the hiss."
A "big rumbling sound" sent Bob Hensel's cats into hiding. He looked long and hard for them before he pried open the garage door to escape the flames. As he drove off, he could see the bumper of his wife's car melt away.
The explosion occurred Thursday evening, sending concrete chunks flying through the air. The heat from the blaze melted tail lights on cars parked blocks away.
In daylight Friday, 15 acres of San Bruno resembled more a war zone than a quiet suburban California neighborhood.
"I was standing next to a police officer who'd been in Baghdad, and he said he had never seen anything quite so bad as this," John Hampton, a freelance photographer who witnessed the fire, told CNN affiliate KGO.
"It looks as if this area was firebombed."
Another photographer, Bryan Carmody, documented the tragedy with his camera lens.
He said the actual gas fire was contained to a small area, but houses just started catching fire, one after another. And the blaze turned into one continuous fireball.
"The fire would just move from one house to the next because the fire was burning so fast and so big and so intensely," he said. "It was definitely a sight to see."
Residents under evacuation orders fled to shelters. Others spent a panicked night in darkness after electricity was cut off. They feared for their friends, families and themselves, not knowing the path and scope of the fire.
On Friday, cadaver dogs were still searching as authorities feared more than four people had perished in the blaze.
Sergio Campos was on his way to class at Skyline College when he saw the fire and pulled over. Even from a distance, he could hear the roar.
But he, like so many other confused San Bruno residents, didn't know whether to run toward the inferno to try to save people, or drive as far away as he could.
CNN's Moni Basu contributed to this report.