There it was, a briefcase sitting on the sidewalk outside the Washington Convention Center, where a military electronics show was about to open. It was a black attache with a metal band around it. A perfect place, James Hutchins said, to conceal a bomb.

Which is exactly what Hutchins, a shift supervisor of security at the center, thought after the briefcase sat unclaimed for 15 minutes. Acting swiftly, he called the police, who in turned called the bomb squad. Then Hutchins cleared the nearest part of the building, and waited.

When the bomb squad arrived, one of its members X-rayed the briefcase and determined that "it contained all the components of a bomb," Hutchins said. They decided to take it to a safe place to blow it up.

But just as they were loading it onto their truck, a man whose computer company will be exhibiting software at this week's show turned up and claimed the briefcase. It held no explosives, he said, just gear he needed for work.

Sure enough, the tangle of wires and circuits in the briefcase turned out "to be nothing," according to a bomb squad member at the scene. "We took it apart, and there was nothing to it," he said. "There were no explosives to be found."

Thus ended a tense episode at the Convention Center, where several thousand workers were setting up for the Armed Forces Electronics Show that begins today.

The owner of the briefcase "had been here earlier and had left, but his boss was still here and heard all the commotion," Hutchins said.

"His boss called him and said, 'Hey, did you leave your briefcase down here?' "

The name of the owner could not be learned.

In an age when terrorists carry explosives onto airplanes and judges and doctors receive package bombs in the mail, Hutchins felt his suspicion was more than justified.

"You just can't take any chances," he said.