WASHINGTON — Packs of motorcycles, dirt bikes and all-terrain vehicles swarmed streets in the District of Columbia and part of the Capital Beltway in Maryland, performing stunts and driving the wrong way on the highway as they terrified other motorists on a balmy afternoon.

Some of the bikers Sunday roared into D.C. from Maryland and turned Georgetown’s signature thoroughfares into a drag strip before racing across the Key Bridge into Virginia.

All along their path, frightened bystanders called 911 and got the same response: no police, at least none that arrived in time to catch anyone.

Much of the spectacle was captured on video that went viral and sparked anger about what people perceived as an impotent response from law enforcement.

Maryland State Police “were immediately dispatched to the area” after getting calls, a spokeswoman said, but traffic had returned to normal by the time troopers arrived.

Troopers then “saturated the area,” spokeswoman Elena Russo said, looking for an estimated 50 to 150 motorcyclists, but found none.

Authorities across the region have concluded that pursuing riders on illegal dirt bikes and similar off-road vehicles is dangerous because law enforcement cannot respond quickly enough or safely chase and corral operators who can outmaneuver police cars.

Motorists caught in Sunday’s free-for-all described a brazen throng, with riders on the Beltway’s inner loop popping wheelies, taking selfies and laying so much rubber that plumes of smoke billowed from the asphalt.

“If they can be identified,” Russo said, “we certainly will be pursuing charges.”

Thrill riders have been a scourge in the District and Baltimore for years, frustrating law enforcement but immortalized on video.