Ravinder Saini, an eyewitness, told a regional TV channel that Champion while entering the residence fired his gun in air, injuring Congress leader Vivekanand Khanduri.
Saini said Khanduri was rushed to a private hospital as he received major injury in his leg while he himself sustained minor injuries.
Police said it was not aware about the incident.
"We are unaware (about firing) but will definitely investigate the (media) queries," said Jagdish Chandra, SP (city).
Party sources said that Champion was not happy with the state cabinet's decision about auctioning of river mining business in the state. Champion, who is also a chairperson of the Uttarakhand Forest Development Corporation (UFDC) was for long demanding UFDC right over mining business.