Trinamul Congress leader and building material supplier Mrityunjoy Bhattacharya, 50, was shot dead at Baruipur on Sunday morning.

Trinamul and the CPM have both called a 12-hour bandh in the area on Monday to protest the murder. One person was detained late on Sunday for interrogation. Police are not sure whether business or political rivalry was the motive.

The shooting occurred around 9 am, while Bhattacharya was opening his shop in the Kulpi Road market. According to a witness, a youth walked up to him with a revolver, shot him and fled.

Passers-by chased the youth but could not catch him. Other shopkeepers and some local residents took Bhattacharya to the Baruipur sub-divisional hospital, where he was pronounced dead.

Local CPM parliamentarian Sujan Chakraborty and Trinamul legislator Arup Bhadra rushed to the spot on hearing about the incident. Police officers, including the sub-divisional police officer of Baruipur, also visited the spot.

Chairman of Baruipur municipality and Trinamul leader Shakti Roychowdhury said that Bhattacharya was a sincere worker of the party. ?He was an amiable man and used to be the ward president. His wife and two children survive him. We hope the murderer is arrested soon,? he added.

Bhadra maintained that a professional killer murdered his party colleague. ?We have called a 12-hour Baruipur bandh tomorrow. The killer must be arrested within 48 hours. If he isn?t, we will start a widespread agitation,? he said.

Chakraborty asserted: ?Bhattacharya?s party affiliation is irrelevant; we cannot allow such killings to continue. We, too, have called a 12-hour bandh tomorrow demanding arrest of the murderer.?

Superintendent of police, (South 24-Parganas) S.N. Gupta said senior officers would investigate the case and interrogate Bhattacharya?s family and friends for leads.