Section 4

the Commissioner of Police or the officer in charge of a division may by order or by giving directions or in any other manner he thinks fit regulate, restrict, control or prohibit the use of any road, street, path or waterway or any public place or close any road, street, path, waterway or public place to the public or any class of the public or to any vehicle or vessel or class of vehicle or vessel;

if it appears to the senior police officer present in any part of such area that, in order to restore or maintain public order in that place, it is necessary to regulate, restrict, control or prohibit the use of any road, street, path or waterway or any public place in or giving access to that part or to close any such road, street, path, waterway or public place and that the situation is too urgent to communicate with an officer having authority under paragraph (a), that officer may exercise the powers conferred by that paragraph on the Commissioner of Police or the officer in charge of a division:Provided that the powers conferred by paragraph (b) shall not be exercised by a police officer below the rank of sergeant.