Hoodlums on Wednesday morning stormed the Senate Chamber during plenary and seized the mace.
The mace is the symbol of authority in the National Assembly without which no decision can be reached on the floor of the legislature.
There was confusion in the chamber as Senators scampered for safety.
Deputy Senate President, Dr Ike Ekeremadu was presiding when the incident happened.
The incident reportedly happened after suspended Senator Ovie Omo-Agege entered the chambers.
In the meantime, security personnel have been deployed around the National Assembly complex to forestall breakdown of law and order.
This is not the not first time such incident would happen the National Assembly, it once happened during the Obasanjo administration when the mace was allegedly taken to Okija shrine.