A bizarre bomb scare caused a commotion near the U.S. Capitol yesterday as police investigated and later blew up a suspicious -- but ultimately harmless -- package found in the back seat of a rental car from Florida.

The driver of the 2005 Chevy Impala told a Capitol Police officer about a possible explosive device about 10:30 a.m., touching off a police mobilization and the closing of surrounding streets. No one was hurt in the episode, which dragged on for nearly three hours.

The driver was taken to an area health facility for mental observation, and a passenger was released. No charges were filed. The identities of the two men were not released.

The driver and his passenger had pulled up to an officer in the 100 block of First Street NW and inquired about parking, according to Sgt. Jessica Gissubel, a Capitol Police spokeswoman. As the conversation continued, the driver mentioned a package in his car "that could be threatening," Gissubel said.

The officer told the driver to pull the car to the side of the road and contacted police commanders about the possible threat, Gissubel said.

Streets around the Capitol were shut down, and the police summoned hazardous materials teams to assess the car and its contents. The Capitol was not evacuated, nor were the Senate office buildings on nearby Constitution Avenue.

But the Labor Department building at Third Street NW was cleared as a precaution, along with a nearby Justice Department building and some commercial buildings along Louisiana Avenue NW.

Cynthia Smith, a secretary at the Bureau of Prisons, was in the cafeteria when she was ordered out of the Justice Department building. She had no time to grab her purse or an umbrella before heading out into the damp, chilly air.

Outside, the sight of police dogs sniffing about and officers flooding into the area did little to ease her nerves. "I'm in no rush," Smith said as she glanced at her watch. "I'd rather be safe than sorry . . . though I'm not sure I feel that safe out here."

Meanwhile, other officers had begun interviewing the two men. Neither is from the Washington area, and it was not clear why they were here, Gissubel said.

Shortly before 1 p.m., officers outfitted in full-body armor began approaching the car to set up a device to detonate, or disrupt, whatever explosive device might have been in the vehicle.

At 1:11 p.m., the package was blown up, sending a brief, cannonlike boom along Constitution Avenue. But the package turned out to be harmless, Gissubel said. At 1:48 p.m., the streets around the Capitol were reopened to traffic, she said.

Staff writers Allan Lengel and Del Quentin Wilber contributed to this report.

Bomb squad members in protective gear walk along Constitution Avenue, near the U.S. Capitol, on their way to detonate a suspicious package in a car.

Law enforcement officers take a close look at the car in the bomb scare. The package turned out to be harmless.