A New Age fire-walking experience gone bad in San Jose this weekend left at least 21 people with burn injuries.

Silicon Valley’s Mercury News is reporting that the event, hosted by New Age self-help guru Tony Robbins at the San Jose Convention Center, sent several people to the hospital and injured dozens more. The firewalking exercise took place at the conclusion of the event,  called “Unleash the Power Within,” when attendees were invited to “turn their fear into power” by walking across a 10 foot-long lane of hot coals.

No sooner did the first person step upon the coals when screams of pain broke through the chanted mantras and shouts of encouragement.

“I heard wails of pain, screams of agony,” said Jonathan Correll, 25, who decided to check it out when heard the commotion and saw one young woman in so much pain “it was horrific.”

“It was people seriously hurting, like they were being tortured,” he said. “First one person, then a couple minutes later another one, and there was just a line of people walking on that fire. It was just bizarre, man.”

Correll, a San Jose City College student, videotaped the scene in which 10 to 15 people were burned before an event staffer told him to put the camera away.

Some people managed to walk across the coals without being burned, such as 19 year-old Henry Guasch who said he felt the power while crossing the coals and chanting his mantra of “cool moss” without being burned. He said the key to avoid a burn is faith and concentration.

Most of the others, including those who thought they walked the coals unscathed, admitted later that their feet did indeed blister after the experience.

“It seemed abnormal that so many got hurt,” said Kim, a 22 year-old who walked the coals.

If you ask Robbins, he’ll tell you the reason they got burned is because they had not yet mastered the concept of turning their fear into power, but scientists have other ideas about why some people get burned and others don’t.

As the Mercury News reports, David Willey, a physics instructor at the University of Pittsburgh at Johnstown in Pennsylvania, has published a text and video on the physics of fire-walking and stated that it “does not need a particular state of mind.”

“Rather, it is the short time of contact and the low thermal capacity and conductivity of the coals that is important,” he wrote. He added that ash that builds up on coals can provide further insulation.

The thickness of the soles of a person’s shoes, the swiftness with which they walk across the coals, the heat capacity of the coals, all contribute to who will or will not be burned when performing this strange exercise.

A statement released Friday from Robbins Research International, said, “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.”

As this blog details, Robbins is indeed well known for his firewalking escapades as well other questionable brain re-reprogramming techniques he employs during his conferences.