Suresh Chandra Yadav alias 'Fauji' was arrested from a roadside restaurant with a pistol and a revolver whose licences have expired, Superintendent of Police Kripashankar Singh, adding that a search is on for his 12 associates.
Suresh assaulted some staff members when they were asked to pay toll charges.
The SP said the arrest was made after the toll plaza authorities had filed a complaint yesterday alleging that Suresh and his aides assaulted some staff members when they were asked to pay toll charges on January 4.
Police are searching 12 other accused on the basis of the CCTV footage, the SP said, adding that Yadav had named some of the party activists involved in the assault.
Asked whether the arrested person is an SP leader, Singh said, "After the SP returned to power, all criminals say that they are leaders of the party," and stressed "law will take its course whether the accused are party activists or not".
Local sources, however, said that Suresh is a leader of an organisation affiliated to the SP.