Three persons were shot dead in a firing between two groups in Shahjahanpur district of Uttar Pradesh on Thursday night, police said.The incident happened at the Aawas Vikas Colony around 8:30 p.m., police said, adding the firing took place after an altercation between two groups near the Kallu Miyan's Dargah.As the firing stopped, four people were seen bleeding profusely. Two brothers identified as Israr and Imran died on the spot while another youth, Musheer, died later, police added.Another youth Rahul aka Sonu was critically injured. He is being treated at a local medical facility.Musheer is relative of the district Samajwadi Party (SP) chief Tanveer Khan.Superintendent of Police (SP) S Chenappa said additional police force has been deployed at the spot and a probe is under way to find the reason behind the killings.