A small bomb damaged an empty military recruiting station in New York City's Times Square early Thursday morning.
The explosion shattered the station's glass entryway. No one was injured.
Authorities said at a news conference that a witness saw a person on a bicycle wearing a backpack and acting suspiciously, but that no one saw a person place the device in front of the recruiting center.
Hotel guests were shaken in their rooms high above the sprawling metropolis around 3:45 a.m. Police were on the scene blocking off the area, stopping traffic and even the subway, while investigating the incident.
"If it is something that's directed toward American troops than it's something that's taken very seriously and is pretty unfortunate," said Army Capt. Charlie Jaquillard, who is the commander of Army recruiting in Manhattan.
He said no one was inside the station, where the Marines, Air Force and Navy also conduct their recruiting efforts.
Guests at a Marriott hotel four blocks away said they could feel the building shake with the blast.
"I was up on the 44th floor and I could feel it. It was a big bang," said Darla Peck, 25, of Portland, Oregon.
"It shook the building. I thought it could have been thunder, but I looked down and there was a massive plume of smoke so I knew it was an explosion," said Terry Leighton, 48, of London, who was staying on the 21st floor of the Marriott.
Yellow police crime scene tape blocked traffic for a few hours. Around the start of the morning rush hour, police began allowing some traffic to pass through what has been called the world's busiest crossroads.
Subway cars were also stopped from passing through the Times Square station during the initial investigation. However, normal service was soon restored, with some delays.
The recruiting station is located on a traffic island surrounded by Broadway theaters and chain restaurants. In the past, it has been the site of anti-war demonstrations, ranging from silent vigils to loud rallies.
The building housing the recruiting station was renovated in 1999 to better fit into the flashy ambiance of Times Square. It's modern styling now uses neon tubing to display a patriotic American flag motif on the office.
For more than 50 years, the station was the U.S. armed forces' busiest recruiting center. It has set national records for enlistment, averaging about 10,000 volunteers a year.
Source: Associated Press