Capitol Police cordoned off several blocks on Friday afternoon after a man seen carrying what appeared to be a shotgun was taken into custody near First and D Streets Northeast.

No shots were fired and no one was injured during the arrest. Several police officers were required to detain the man.

A green pickup truck that U.S. Capitol Police spokeswoman Sgt. Kimberly Schneider said was “associated” with the arrested man was also under investigation by the Capitol Police bomb squad after officers reported seeing wires in the truck that could have been part of an explosive device.

Late this afternoon, bomb squad members created a loud boom in an attempt to trigger any potential explosive. Bystanders reported hearing only the boom, but no explosion.

Television footage later showed a bomb squad officer walking around the vehicle, whose driver-side door was open and whose contents were scattered on the street.

“We’re still in the process of clearing the vehicle,” Schneider said in an e-mail message at 6:10 p.m. “Hopefully, we’ll release the perimeter soon.”

Earlier today at a mid-afternoon news conference, Schneider said police were investigating the vehicle to determine if there was anything inside “of a hazardous or suspicious nature.” Part of the investigation was performed by a bomb squad robot.

“Our main concern right now is to make sure the public is safe,” Schneider said at the news conference, explaining why police had cordoned off what she called a “huge perimeter.”

The suspect, a white male who has not been identified, was being questioned at Capitol Police headquarters late Friday afternoon, Schneider said.

Schneider added that the man was thought to be alone.

“We believe we have the sole person in custody. … The threat is neutralized. We are investigating the vehicle.”

Officers cordoned off a large area roughly bordered by Union Station on the north and Constitution Avenue on the south. Streets also were blocked off as far west as First Street Northwest. One side of the Teamsters building near Louisiana Avenue Northwest also was evacuated before bomb squad officers were able to test the car for any explosive device.

— Elizabeth Brotherton and Emily Yehle