The Economic and Financial Crimes Commission (EFCC) has picked up Senator Rochas Okorocha from his residence.
The agency had broken into the residence after gunshots were heard in the vicinity.
The EFCC had also insisted that journalists must leave the premises, forcefully ejecting everyone in the residence.
A Channels Television cameraman, Kabiru Owoyemi, was among those brutalised during the clearance. He was hit with a gun on the neck.
The operative also used teargas to disperse journalists from the scene.
