Maryland State Police and Anne Arundel County police are searching for an armed man near Glen Burnie, Md., on southbound Route 295 near Interstate 195 and the exit for Baltimore-Washington International Thurgood Marshall Airport.
Police received reports at 11:30 a.m. of a man wielding a long gun, believed to be a shotgun, and a hammer.
The man walked out of the woods along the Baltimore-Washington Parkway and up to a Jeep SUV operated by a speed camera contractor late Wednesday morning, said Greg Shipley, a Maryland State Police spokesman. When he tapped on the back window with the gun, the contractor became startled and began honking the Jeep's horn. The gunman walked to the front of the vehicle, pounded two holes in the windshield with a hammer and yelled incoherently, Shipley said. The contractor then jumped out of the vehicle and crouched near a guardrail, authorities said.
Then just as suddenly as he had appeared from the woods, the gunman disappeared into them, NBC Washington's Tracee Wilkins reported.
Several motorists witnessed the incident and called it in to authorities.
Police are looking for a gray-haired white man in his 50s or 60s with clear glasses and wearing a blue and red shirt -- possibly flannel -- and blue jeans, authorities said. He stands about 6-feet tall and weighs about 200 to 220 pounds, possibly with a potbelly. He may have had a dark-colored backpack.
About 50 officers were searching for the gunman. Police used dogs and helicopters to aid in the search. Both departments deployed SWAT teams.
There was no evidence that shots were fired, and no one was injured, Shipley said.
The Baltimore-Washington Parkway was shut down for the search but reopened before 3 p.m. The State Highway Administration diverted traffic at Interstate 695 to the north and Route 100 to the south.
Police believe the gunman may have walked through the woods to a parking lot in the 1300 block Concourse Road, got in a vehicle and left the area. Anyone who was in that area between 11 a.m. and noon Wednesday should contact police.
State highway crews are in the midst of a lengthy project to widen the parkway in both directions between I-195, the access highway for the airport, and I-695, the Baltimore Beltway. Speed cameras are authorized in the work zone, as they are in other highway work zones in Maryland. Signs alert drivers to the presence of the cameras.
Anyone with information about the incident or a possible suspect should call 911 or Maryland State Police at 410-761-5130. Police want to talk to anyone who stopped on the BW Parkway to watch the incident.
Stay with NBCWashington.com for more information.