Maharashtra Navnirman Sena (MNS) chief Raj Thackeray was arrested at Ratnagiri in the wee hours on Tuesday for Sunday's brutal attack on north Indian rail exam candidates by MNS workers. A case was registered in this connection against Raj Thackeray and his supporters at a North-West suburban police station of Kharwadi, after MNS workers attacked 13 railway board examination centres in suburban Mumbai to protest against "inadequate representation" to locals.