Austrian authorities said Tuesday they arrested a second suspect in an attempted bombing of the U.S. Embassy in Vienna.
Officials said they were treating him as a possible accomplice of a Bosnian arrested Monday after trying to enter the embassy with a backpack containing explosives.
Police said they took a man into custody Monday night in the town of Tulln, about 25 kilometers (15 miles) west of Vienna.
The nationality of the second suspect was not immediately released, but investigators said the two appeared to know each other.
The 42-year-old Bosnian was arrested Monday after his bag - packed with at least two grenades and several handfuls of nails and screws apparently intended to serve as shrapnel - set off a metal detector at the entrance to the heavily fortified embassy.
He fled on foot but was captured a short distance away after tossing the backpack into the street. It did not explode, and no one was injured.
Police said the Bosnian-born man, who has been living in the province of Lower Austria, was also carrying a book that contained references to Islam.
Muslims comprise the predominant ethnic group in Bosnia-Herzegovina, and though the vast majority are moderate or secular, authorities there have been monitoring individuals who have become radicalized and are believed to have ties to extremists.
But Doris Edelbacher, chief spokeswoman for Austria's federal counterterrorism office, played down speculation Tuesday that the would-be bomber may have been motivated by radical Islamic ideology.
Edelbacher said the Bosnian was incoherent and rambled to police during an interrogation that lasted deep into the evening. The suspect "really confused things," she said without elaborating.
Experts were still analyzing the book, Edelbacher said.
The motive for the bombing attempt remained unclear. U.S. Embassy officials did not return telephone messages from The Associated Press seeking comment.
Rather than blow up the backpack in a controlled explosion, a police bomb squad used a water cannon to partially tear it open so the contents could be preserved and examined, officials said.
"There were a lot of nails in that bag. Had it exploded, it would have had an enormous shrapnel effect," Edelbacher said.
Guenther Ahmed Rusznak, a spokesman for Vienna's Islamic community, issued a statement late Monday condemning the incident and rejecting radical Islam.