Thirteen people attending a company gathering were hospitalized after a group of 25 people suffered burns on their feet after walking over hot coals on the banks of Lake Zurich in Switzerland, according to a Swiss police statement. Ten ambulances were dispatched to a private event at around 6 p.m. Tuesday after organizers called for help. All 25 people at the event were treated for burns after walking barefoot for several meters over the coals. Police are investigating whether the incident was an accident or part of a ritual challenge. Fire-walking over burning coals, hot embers, or baked stones is often used in motivational exercises, or as a personal challenge. It is also sometimes used in team-building seminars to strengthen trust.