A video footage, which has gone viral on the social media, shows a group of people raising "anti-India" and "pro-Pakistan" slogans after the declaration of the bypoll results on Wednesday, they added.
Taking cognizance of the video, the Station House Officer (SHO) of Araria town police lodged an FIR against a group of persons -- three named, the rest unidentified -- under various sections of the IPC and IT Act.
"Two persons named in the FIR -- Mohammad Shahzad and Mohammad Sultan -- have been arrested. The third accused, Mohammad Abid, will be nabbed soon," District Magistrate, Araria, Himanshu Sharma said.
The video showed the sloganeers flashing the victory sign near Alam's residence.
Alam had defeated the BJP's Pradeep Kumar Singh by over 60,000 votes in the bypoll.
Reacting to the development, Leader of Opposition in the Bihar Assembly Tejashwi Yadav said in Patna, "Let the matter be thoroughly investigated. Videos that go viral are not always authentic. Moreover, those named as accused may not necessarily be our party workers."
Stating that he had spoken to Alam, who had told him that no victory celebrations were organised by him, the RJD leader said, "On occasions like these, people gather on their own. In a crowd, anybody can cause a mischief. Moreover, the BJP has been carrying out a smear campaign against us, describing our victory in Araria as a boost to terrorist activities."
Yadav also took strong exception to Union minister Giriraj Singh's statement that the RJD victory would convert Araria into a terrorist hub.
"Does he not remember that the seat was with the RJD since 2014, when Alam's father, the late Mohammad Taslimuddin, got elected from there? Was it a terrorist hub during that period? If yes, what was the government, of which Singh is a part, doing," he said.