Shiv Sena (Taksali) leader Sudhir Suri was shot dead on Friday while he was taking part in a protest outside a temple in a busy Amritsar locality, police said.
More than five shots were fired at Suri after which he fell down and lost consciousness. He was taken to a hospital where he succumbed to bullet injuries, they said.
The accused, Sandeep Singh, has been arrested and the weapon used in the crime seized, police said.
Suri was protesting against the management of Gopal Mandir on Majitha Road -- one of the busiest places in the city -- after some broken idols of Hindu deities were allegedly found on the roadside, which he termed a sacrilege act.
The Shiv Sena leader was in the hit list of several gangsters for a long time. He was provided security by the government with around eight Punjab Police personnel being attached with him, they said.
He had allegedly been raising his voice against some Sikh fundamentalists as well.
Speaking to reporters here, Amritsar Police Commissioner Arun Pal Singh said, “Suri was staging a protest outside the Gopal Mandir at Majitha Road. The assailant arrived on the spot and opened fire at him. Multiple shots were fired at Suri leaving him seriously injured and he was shifted to a hospital where he succumbed to injuries”.
The assailant was identified and nabbed on the spot by Suri's security guards, he said.
"The licensed weapon of the assailant was also seized," the police commissioner said.
Police said the alleged accused was a resident of Sultanwind area of Amritsar city.
He is being interrogated by a team of Punjab Police officers and intelligence agencies officials to bring out the motive behind the killing, they said.
After the incident, opposition Congress and BJP targeted the Bhagwant Mann-led AAP government in the state, with Punjab BJP president Ashwani Sharma alleging that the law and order situation has completely broken down in the state.
"Political differences apart, violence is unacceptable. Culprits must be brought to book," Congress president Amrinder Singh Raja Warring said in a tweet.