NEW DELHI: One of the coaches of Olympic boxing champion Mary Kom Hemlata Gupta , was allegedly beaten up by the staff of a restaurant in Udaipur. Four people were detained on Tuesday after an FIR was filed in this regard.According to the Ambamata police, the incident occurred at the Ambrai restaurant in Udaipur on Monday. Hemlata's family was also beaten up and her mobile phone worth Rs 40,000 was stolen. When Hemlata informed the restaurant staff that her phone could not be found, the employees assaulted the family.The officer in charge of the investigation, sub-inspector Ram Lal Gurjar, said the manager and three waiters had been detained. He said Hemlata's phone was recovered from the restaurant's compound on Monday night.Hemalata Gupta was on holiday in Udaipur with her husband and in-laws.