Two persons have been taken into custody in connection with the killing of Ashok Jaiswal.
A local BJP leader, Ashok Jaiswal, was shot dead by unidentified gunmen at Bihar's Danapur, the backyard of state capital Patna, on Wednesday evening.
The assailants had pumped four bullets into the body of Mr Jaiswal, said senior police officer Rajesh Kumar. He died at a private hospital.
Two persons have been taken into custody in connection with the killing, the officer added.
The BJP's Union Minister of State Ramkripal Yadav, who visited Mr Jaiswal's home, said the murder was a reflection of the deterioration in law and order situation in Bihar. The party has called a strike in the area in protest against the murder, he said.
"The murder of Jaiswal in a busy place is enough to prove that criminals do not have any fear of law in the state under the Grand Secular Alliance government," he said.
Mr Yadav, a lawmaker from Patliputra, Danapur legislator Asha Devi and Digha legislator Sanjeev Chaurasia hit the streets in protest against the killing of Mr Jaiswal.