As she drove to work, Genevieve Alba could see the flames churning through the mountains above Altadena. They looked far off, and with a funeral the next day, there was still plenty to do.

A woman needed to be prepared for the service, a careful embalming task that Ms. Alba began around 3:30 a.m. in a windowless room at the Mountain View Mortuary and Cemetery. The smell of smoke was getting worse and worse, but Ms. Alba thought little of it as she focused intently on bathing the woman and setting her features.

Then, as the sun began to rise, her boss flew into the room in a panic. The town, he told her, was on fire. They rushed outside and saw home after home consumed by flames.

“The sky was just red and there were explosions everywhere,” recalled Ms. Alba, 30.

At a cemetery, there is a lot to consider when flames are upon you. Employees thought of their own safety, yes, but also felt a duty to those who entrusted them with their recently departed loved ones.

In the moment, the employees’ first thought was of the formaldehyde. They began loading boxes of the flammable embalming chemical into a van, and an employee drove it to the center of the cemetery, away from any buildings or people, like getting rid of a grenade.