Spent cartridges of a 9 mm pistol and 7.6 mm pistol were found from the spot.
Mohanty fell from his bike, when the bullets hit him. He had severe injuries on his head, face and legs.
He was rushed to Puri district hospital, from where he was shifted to Kalinga Hospital in Bhubaneswar at around 11:55 pm.
The lone witness Susanta Kumar Sahu, a betel vendor, who ran after the assailants soon after the attack, but failed, had returned to his home in Bakery Line, but late at night three youths on two bikes came to his house and abducted him, his brother Hemant Kumar Sahu said.
Maheshwar Mohanty, who has been an MLA from Puri consecutively since 1995, is the Law, Planning and Coordination, Tourism and Culture Minister.
He was also the Speaker of Odisha assembly earlier.
Director General of Police Prakash Mishra has formed a special team which rushed to the seaside pilgrim town in a bid to trace the assailants.
Mohanty was attacked with an axe on his head during an election meeting in Chandanpur near Puri in January, 2012.
