Motorcycles and dirt bikes pop wheelies and drive the wrong way, slowing traffic on the Capital Beltway Sunday, Dec. 27. Officials took no enforcement action, according to Maryland State Police. (Jukin Media, Inc.)

Packs of motorcycles, dirt bikes and all-terrain vehicles swarmed streets in the District 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 the District from Maryland, drove through the NoMa neighborhood and turned Georgetown’s signature thoroughfares of M Street and Wisconsin Avenue in Northwest 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 and escape on stairs and sidewalks and through narrow alleys.

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 as if fires had been set up and down the road.

“It was just not right that traffic would be stopped at the whim of a few hundred motorcycles,” said Alyssa Ruth, 27, who was headed home to Raleigh, N.C., with her husband and their Jack Russell terrier, Eddie, when they were caught in the traffic jam.

“It was really surreal. Just the scale of it,” she said. “It had this strange, lawless feeling.”

Ruth took video from the window of their Toyota Prius, capturing the smoke and people hanging out of car windows to watch and cheer as motorcycles, ATVs and street bikes tried to block lanes. She told her husband to lock the doors when riders weaved close to their car.

State police are analyzing videos and will look at license plates, along with faces and tips from witnesses, to try to find those involved. But Russo, the police spokeswoman, said many of the vehicles did not have plates.

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

One member of a motorcycle group said the group was riding lawfully around the Beltway when it was infiltrated by bikers from Baltimore who disrupted traffic with “crazy stunts” that “made us look real bad.”

Del Thompson, 35, of the District, said he was among 75 or so motorcyclists who occasionally organize rides over social media. This past weekend’s outing was called Fun Day Sunday, Let’s Everybody Ride. Thompson said all of their motorcycles are properly licensed, and they rode two loops around the Beltway before the Baltimore group appeared.

“They were driving like crazy,” Thompson said. “It was a fun ride until they came along. They were making videos.” He said it was the Baltimore group that broke off and headed into Georgetown and Arlington.

Thrill riders have been a scourge in the District and Baltimore for years, frustrating law enforcement but immortalized on video and in documentaries including a British film about the 12 O’Clock Boys of Baltimore.

Police are trying to find ways to stop the riders before they start or to apprehend them after they have wrapped up.

D.C. police encourage residents to report unregistered or illegal bikes by offering a $250 reward.

In North Baltimore this summer, when as many as 3,000 people flooded a park to watch riders on a Sunday afternoon, police tried to close parts of a major road and put up obstacles to slow the drivers and prevent trick moves. Baltimore officials also have proposed a grand-prix-style track for dirt bike riders as an alternative to the streets.

Police in different jurisdictions point to the dangers of the dirt bikes and police interaction. In May, a spectator was struck and killed by a dirt bike in Baltimore, and another man was killed in September when his dirt bike collided with a van. Last year, a 17-year-old was killed when a dirt bike he was riding hit a tree in the District during a pursuit by Prince George’s County police. They said at the time that the bike had been linked to an armed robbery.

Bystanders say police can do more to stop the riders.

Donavan Albert, 45, who lives in Montgomery County, said he and his wife visited Georgetown on Sunday evening and were walking on the sidewalk when they heard a loud noise and realized that 20 to 30 riders — about half on ATVs or four-wheelers — were popping wheelies along M Street near Wisconsin Avenue NW.

Albert said he saw two police cruisers in the area and that the officers did nothing. “It was so surreal,” Albert said. “It was hard to believe it was happening in the nation’s capital. It looked like anarchy and chaos. . . . It felt like ‘Mad Max’ road warriors.”

Robin Cook, 63, said he saw the group in Arlington as he walked his dog near the Key Bridge. Some were getting gas, he said, while others rode in circles on nearby streets, blowing through red lights and driving on sidewalks.

“They were violating just about every traffic law imaginable,” Cook said. He called police but said no one came. “How can the police confronting them be any more dangerous than what they were doing?” he said.

Dustin Sternbeck, spokesman for the Arlington County Police Department, said his agency received several calls about the group Cook saw but that the riders were gone by the time officers arrived. He noted that, with 12 to 18 officers on duty at any given time, chasing or rounding up 100 motorcycles is dangerous and nearly impossible.

Sternbeck said the motorcyclists typically enter Virginia from the District by taking the Key Bridge into Rosslyn and quickly get on the George Washington Memorial Parkway. “They’re in Arlington only a couple of minutes,” he said.