It was one of the deadliest wildfires in U.S. history, killing 19 members of the elite Central Arizona Fire Brigade in 2013 when the flames were trapped in a bush-covered ravine.

The city of Prescott and the neighboring town of Yarnell will commemorate the deceased Granite Mountain Hotshot at a public event Friday. Lou Theokus, who lost his grandson, Garrett Zuppiger, 27, said he still finds it difficult to talk about the Yarnell Hill fire 10 years later.

“He was my only grandson, my only grandson,” said Theokas, who was with his wife in Oklahoma the day his grandson died. “We were on an RV trip and were due to be back in town in two days. I spoke with Garrett that morning.”

When the fire broke out, dry lightning struck the steep mountainous vegetation zone, igniting a fire high on the ridge west of Yarnell, which had not had a wildfire in over 45 years.

Two days later, as the Hotshots were battling wildfires in Box Canyon, the wind suddenly changed and the flames rushed toward them. Nineteen attempted to set up emergency shelters, tent-like structures designed to protect firefighters from flames and heat.

Gusts and hot air swelled the blaze to more than 2,000 degrees Fahrenheit (1,093 degrees Celsius), blocking firefighters’ escape routes and killing the men, officials said.

The only surviving crew member, Brendan McDonough, was stationed away from the group as a lookout when flames struck the other Hotshots. McDonough will read the same prayer he recited at the Hotspot memorial service, which drew people from around the world, including then-Vice President Joe Biden.

The Yarnell Hill Fire is the deadliest wildfire since the 1933 Griffith Park fire in Los Angeles, which killed 29 firefighters, and the deadliest firefighter loss since the September 11, 2001 terrorist attacks. became.

The Yarnell fire charred more than 13 square miles (33.6 square kilometers) and destroyed 127 buildings.

The Arizona Forestry and Fire Department said it found no evidence of negligence or recklessness on the part of the firefighters after a three-month investigation.

The investigation cited some radio communication issues due to heavy radio traffic and some radios not having proper tone guard programmed.

The Arizona State Industrial Commission, which oversees workplace safety, fined the Forest Service $559,000 for failing to remove Hot Shots before the tragedy struck.

Arizona fire chief John Tuett said advances in technology have helped firefighters since then.

“We have GPS and satellites and more robust communications,” Tuyet said. “I didn’t know where the firefighters were.

Theokas, a 12-year veteran who served in the People’s Valley Fire District just north of Yarnell, said his district formed a wildfire division in response to the tragedy and is better equipped to fight wildfires. . In recent years, crews have removed thick shrubs and bushes to remove fuel that causes the most violent fire behavior and to protect homes and other structures.

A 9-foot (2.7-meter) tall photo at the Yarnell Hill Fire Memorial Park shows Granite Mountain Hotshot posing with a human pyramid. Among the firefighters, 14 were in their 20s.

“I live in the community and when I pass by the monuments in the park, it never leaves my mind,” says Theokas. “These boys were all cut from the same cloth. The pictures of the boys were cut into stainless steel plates. It never fades and you can always see them together.”

Earlier this month, Yarnell held a memorial service and launched a commemorative exhibition of paintings, photographs, poetry and mementos recovered from the fire.

On Friday, the memorial team will host a public memorial service honoring the firefighters. Arizona Governor Katie Hobbs is scheduled to speak alongside other dignitaries at an event at the Yavapai County Courthouse in Prescott, where the local honor guard will ring 19 bells.

Gray Stafford, an adjunct professor at Grand Canyon University in Phoenix and an adjunct paramedic for the Peoples Valley Fire District, said a decade later the tragedy still permeates the community.

Stafford, a new resident who was due to attend Yarnell’s memorial service, said: “Everyday life is normal, but the event is always there like a low cloud.” “The legacy of the Yarnell Fire remains and extends beyond Yarnell to surrounding areas such as People’s Valley where residents have lost friends, family, colleagues and even their homes, livelihoods and other possessions.”

Theokas also expected to attend the event, although he said it would still cause heartache.

“I just turned 71. I have no grandchildren,” he said. “I tell all my friends who have grandchildren that they envy that part of their lives.”