"Initially, Vasai MLA Kshitij Thakur and then legislator Ram Kadam surrendered before us at the police headquarters here and their statements are being recorded," a crime branch official said.
"The formalities to arrest them are underway. After their arrest, the duo will be produced before a local court later in the day," the official said.
On March 19, an FIR was registered at Marine Drive police station against Thakur, Kadam (MNS) and 14 others for allegedly beating the 31-year-old police sub inspector with Worli Traffic Police at Vidhan Bhawan.
Later, crime branch took over the investigations. Suryawanshi had allegedly stopped the vehicle of Thakur a day before on the Bandra-Worli Sea Link when the MLA was on his way to attend the Legislative Assembly Session.
Thakur was reportedly fined because his vehicle had exceeded the speed limit.
There was an altercation between the legislator and the policeman, during which the latter allegedly misbehaved with the MLA.
Following the incident, the policeman was thrashed at the entrance to the visitors gallery in the the House, by a group of legislators including Thakur, Kadam, Rajan Salvi (Shiv Sena), Pradeep Jaiswal (Independent), among others.
The accused have been booked under IPC sections 143 (unlawful assembly), 341 (wrongful restraint), 353 (assault or criminal force to deter public servant from discharge of his duty), 504 (intentional insult with intent to provoke breach of peace), 323 (punishment for voluntarily causing hurt) and 506 (ii) (criminal intimidation), sources said.
Suryawanshi, who is undergoing treatment at the St George hospital in South Mumbai, yesterday said in a statement that he was attacked by the legislators after he had come out of Legislative Council Deputy Chairman Vasant Davkhare's office on the first floor and was sitting on a bench, about to leave for the canteen.