Austria ? A Bosnian who tried to enter the U.S. Embassy in Vienna with a backpack filled with explosives, nails and Islamic literature was arrested Monday after the bag set off a metal detector and the man fled on foot, authorities said.

Police sealed off the neighborhood as a precaution and shut down or rerouted nearby bus and tram lines. Officers patrolled the area with bomb-sniffing dogs.

The suspect was described only as a 42-year-old native of Bosnia-Herzegovina who now lives in the province of Lower Austria, which encircles most of the capital. Police said they made the arrest a short distance from the embassy in a neighborhood where security is tight.

“There were a lot of nails in that bag. Had it exploded, it would have had an enormous shrapnel effect,” said Doris Edelbacher, of Austria’s federal counterterrorism office.