N.Y. Second Class Cities Law § 57
The mayor shall have such other powers and perform such other duties as may be prescribed in this chapter or by other laws of the state or by ordinance of the common council, not inconsistent with law. In case of riot, conflagration or other public emergency requiring it, the mayor shall have power to call out the police and firefighters; he or she shall also have power to appoint such number of special police officers as he or she may deem necessary to preserve the public peace. Such special police officers shall be under the sole control of the regularly appointed and constituted officers of the police department. They have shall have power to make arrests only for disorderly conduct or other offenses against peace or good order. In case of riot or insurrection, he or she may take command of the whole police force, including the chief executive officer thereof.
N.Y. Second Class Cities Law § 57