Police said they have arrested four protesters, including a lawmaker, when they went to set a police station on fire at Gair Kalawasi village in Sarlahi district on Saturday. Police identified the lawmaker as Jangilal Ray Yadav of Tarai Madhes Democratic Party. The other arrestees have been identified as TMDP cadres Binaya Karna, Avinash Sathi and Bijaya Yadav, DSP Ramesh Kumar Khadka said. Yadav was elected to the Constituent Assembly from Sarlahi Constituent No 5. They face vandalism and arson charges. An eight-member group led by the lawmaker had hurled a petrol bomb on the police post at around 4 pm today, according to police. Security personnel lobbed tear gas shells to disperse the mob and called for additional troops from the District Police Office. DSP Khadka added that security has been beefed up in the district considering violent protests by the Madhes-centric parties. An agitating group had set a police post in Haripurwa of the district on Friday.