The Duke and Duchess of Sussex donated supplies, served meals with the World Central Kitchen in Pasadena, California, thanked first responders and met with affected families as they took in the devastation caused by the fires.
"It's great people, great personalities and great heart for them to come out here and meet with the first responders, meet with the people who were affected," Pasadena Mayor Victor Gordo told reporters.
"It's very important. They really buoyed the spirits of the first responders.
"People were very happy to see them. They want to be as helpful as they can be … we visited with some of the affected families in some of the burned-out areas in Pasadena and Altadena.
"They took the time to meet the people that are affected and spent time.
"They're just very caring people who are concerned for their friends and neighbours."
Pasadena Mayor Victor Gordo (centre) says Meghan Markle served food "anonymously" to fire victims. (AP PHOTO)
He said Harry and Meghan's appearance was not for "publicity" and said they served food "anonymously" earlier in the day.
"No one knew they were serving food with masks," he said.
"We went to visit some of the families in the impacted area and view firsthand some of the impacted area and then they wanted to go visit the first responders and personally thank them for their efforts to help our families and their neighbours."
It was previously reported that Harry, 40, and Meghan, 43, opened their home to friends fleeing the wildfires.
The royals are believed to have offered their $US14 million ($A23 million) mansion in Montecito as a refuge to pals and loved ones who have been forced to evacuate their homes due to the fires, which have forced more than 100,000 residents of Los Angeles to seek safety.
According to PEOPLE, Meghan and Harry - who live about 145km north of the affected area - "have opened their home to friends and loved ones forced to evacuate".
The couple also issued a statement telling residents how they could keep pets and vulnerable residents safe amid the disaster.
"In the last few days, wildfires in Southern California have raged through neighbourhoods and devastated families, homes, schools, medical care centres, and so much more - affecting tens of thousands from all walks of life," they said.
"A state of emergency has been issued. If you feel compelled to help, here are some resources and ideas.
"If a friend, loved one, or pet has to evacuate and you are able to offer them a safe haven in your home, please do.
"And be sure to check in with any disabled or elderly neighbours to see if they need help evacuating. Some families and people have been left with nothing.
"Please consider donating clothing, children's toys and clothing, and other essentials.
"The American Red Cross is on the ground helping those in need."
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