A man locked himself in a house and threatened to shoot self with a gun at Kilpauk area in the city since morning, police said.
He is allegedly holding a woman as hostage, they said.
Police are negotiating with Vijayakar, who had also fired in the air earlier following a tiff with his neighbours.
The man is suspected to be mentally deranged as he was seen making incoherent statements, police said.
Armed policemen and Special Action Force personnel have been posted in the area. Medical teams are also stationed.