In Arizona, a solemn 100-mile procession for fallen firefighters

(CNN) -- A procession of 19 white hearses left Phoenix on Sunday carrying the bodies of Arizona firefighters who died battling wildfires last week.

People with no personal connection to the 19 fallen Granite Mountain Hotshots traveled from across the state and around the country to pay respects. Crowds of people waving American flags lined the streets of Phoenix for the start of the nearly 100-mile public procession to Prescott, the unit's hometown.

"These men are heroes. They've earned the respect of everyone in this line," an onlooker told CNN affiliate KTVK as he awaited the procession in Phoenix.

The elite team of first responders died as they battled the Yarnell Hill Fire, which was sparked by lightning some 3.5 miles west of Yarnell. The incident, part of a fire that has destroyed more than 100 homes over 13 square miles, was the deadliest day for firefighters since the 9/11 attacks. As of Sunday, at least 90% of the fire had been contained, officials said.

Hotshot crews are called to get close to the blaze, dig barriers and clear out the brush and other material that otherwise would fuel it. Erratic winds were blamed on the sudden shift in the fire's direction that trapped the group. The deaths are under investigation, but officials have said it appears the 19 were forced to lie down under blankets meant to protect against flames and heat as a last resort against an inferno that overwhelmed them.

The procession of hearses and police motorcycles passed through Yarnell on its way to Prescott, where the team will be laid to rest Tuesday in a memorial that Vice President Joe Biden is expected to attend.

The firefighters left behind wives and children. One firefighter left behind his pregnant fiance.

"I feel for the people they left behind," an observer of the procession in Phoenix told KTVK. "There's a story behind each family. The more I hear, the more sad it makes me."