A policeman posted to guard a road through which Prime Minister Manmohan Singh's motorcade was to pass, accidentally fired a bullet injuring a labourer on Thursday.
The injured labourer was being taken to the Guwahati hospital by the chief minister's helicopter, Superintendent of Police Hibu Tayang said.
He said the bullet went off accidentally from the service revolver of an Indian Reserve Battalion constable who was posted near the Indira Gandhi park where the prime minister is scheduled to address a public meeting.
A case was registered against the constable, the SP said.
The prime minister will arrive in Itanagr on Thursday on a two-day visit to Arunachal Pradesh.