A man threatened to blow himself up on a Potomac River bridge near downtown Washington, D.C., blocking a major traffic route for nearly seven hours before surrendering. Police armed with rifles surrounded Sadiq Abubakar, threw a net over him and shoved him into a police van after he got out of his Mercedes-Benz sedan, which had been blocking the 14th Street Bridge at the height of rush hour on Monday. As traffic piled up, Abubakar, who is divorced, handed police a note saying he had an explosive device in the car and wanted to see his daughter. Police witnesses said he had a sack on the front seat, but they did not know whether it contained explosives. Police initially communicated with Abubakar through megaphones but a police robot later was used to wheel out a phone. Abubakar, who is Nigerian-born, spent the next several hours negotiating with police.