(Reuters) - Nearly two dozen people were treated for burns on their feet after walking on hot coals during a motivational seminar conducted by self-help expert Tony Robbins in San Jose, California, local media reported.

Firefighters treated at least 21 people for burns to the soles of their feet, several of them second- and third-degree, on Thursday night, according to a report in the San Jose Mercury News. None of the injuries was life-threatening, the report said.

It was the first night of the motivational seminar called “Unleash the Power Within,” a four-day Robbins event attended by some 6,000 people, the Mercury News reported.

Phone calls to San Jose fire and emergency officials were not immediately returned, and Robbins could not be reached on Saturday through his media contacts.

In a written statement reported in the Mercury News, Robbins Research International defended the “firewalk,” a regular part of the Unleash seminar.

“We have been safely providing this experience for more than three decades, and always under the supervision of medical personnel ... We continue to work with local fire and emergency personnel to ensure this event is always done in the safest way possible.”’

The firewalk is presented on Robbins’ website as a way to conquer fears and “other fires in your life” by walking across a bed of coals heated up to 2,000 degrees. It is not a requirement of the seminar.

The first day of the event ended on Thursday night at the San Jose Convention Center, after which attendees crossed the street to a park equipped with 12 lanes of hot coals measuring 10 feet long and 2 1/2 feet wide, the Mercury News reported.

It was unclear how many people participated in the firewalk.

Considered one of the world’s most successful self-help experts for nearly three decades, Robbins oversees an empire of self-empowerment seminars, books and tapes, life coaching and motivational presentations.