Since the violence started, police have arrested 18 people based on video footage and witness accounts.
A Trinamool Congress leader and four BJP members are among 19 people arrested for throwing stones at Meghalaya Chief Minister Conrad Sangma's office on Monday.
Richard Marak, who was a TMC candidate from South Tura constituency against Mr Sangma in the 2023 Meghalaya Assembly elections, has been arrested by the Tura Police in connection with mob attack at the office of the Chief Minister. 18 personnel of security forces were injured in the attack.
Four BJP members, including two from BJP Mahila Morcha (women's wing), are also among those arrested. BJP is an ally of Conrad Sangma's National People's Party (NPP), and a part of the coalition government in the state.
Hundreds of people gathered outside the Chief Minister's office and started throwing stones last evening. Five security personnel were injured in the attack. They were brought inside Mr Sangma's office.
Visuals showed the injured security personnel lying on the floor, while Mr Sangma tended to them.
Garo Hills-based civil society groups have been on a hunger strike demanding for a winter capital in Tura.
"Discussions were going on, we had already agreed to meet in Shillong to further discuss the matter with all stakeholders, and the NGOs seemed more or less satisfied. A majority of the society and NGOs were not part of this fasting protest, only two-three of them were there. 90 per cent of the organisations weren't part of this," Mr Sangma said in a video statement.
"Even then, I believe that dialogue is important. Hence, I made a point to meet them. After the discussion was almost over, we heard sloganeering from outside. I asked them not to create any scene out here. Their leaders (of the NGOs in talks) went outside to speak to the people. They came back and said they did not know who these people were, never seen them before during the fasting protest," Mr Sangma said, adding the leaders themselves took shelter inside as they were unable to leave.
According to sources in the Chief Minister's office, certain groups surrounded and threw stones at the Chief Minister's Secretariat on Monday evening when Conrad K Sangma was having a peaceful meeting with NGOs and pressure groups that were on an indefinite hunger strike.
Since the violence started, police have arrested 18 people based on video footage and witness accounts for inciting the unruly mob. With Mr Richard's arrest, the tally has gone up to 19.