The shocking incident took place late last night at Pilapur village of the district when some unidentified bike borne persons shot dead the groom Sudhir Kumar, 22 just after the "Jaimal" ceremony.
The unidentified miscreants shot dead the groom when he was going to sit in his car after the "Jaimal" ceremony.
The family members took the groom to the Ara sadar hospital where doctors declared him brought dead, police said.
The deceased's cousin Azad Singh today lodged an case against some unknown persons with Jagdishpur police station.
"An FIR was lodged today in connection with the murder case against some unknown persons," Superintendent of Police Kshatraneel Singh said adding that no arrest has been made so far in this regard.
The groom had died on the spot last night, Mr Singh said.
The exact reason behind the killing could not be known so far, he said adding that police are investigating the case from all angles.
Mr Kumar and his family members had reached Pilapur village with nearly 50 of their friends and relatives for his wedding.
The incident occurred when Kumar, the groom, was going to sit in his car after "Jaimal" ceremony when suddenly some unidentified persons shot him hitting in his back, police said adding that the killer escaped taking advantage of the darkness.