As many as 30 ATV riders surrounded and stopped an ambulance transporting a sick child on Monday, and over the weekend a D.C. police officer was hit by a group of ATV riders, police said.

The incidents come after many others involving ATV s and dirt bikes in the Washington, D.C., region. Local and federal agencies have said they are teaming up to stop ATV and dirt bike riders who are riding on streets illegally and taking them over across the region.

An alert was sent out to fire departments on Monday after the attack on the ambulance, which was stopped by ATV riders while transporting a child to Children's National Medical Center in Northwest D.C.

One of the ATV riders opened the door to the ambulance and accused the ambulance driver of cutting him off, according to D.C. police.

The ambulance driver called 911. It wasn't until police arrived that the ATVs dispersed and allowed the ambulance to continue, police said.

In a separate incident over the weekend, a D.C. police officer was hit by a group of ATVs. The officer was struck by an ATV and dragged down a street in Southeast D.C., police said.

"They come back every summer," Police Chief Cathy Lanier said.

Lanier said there is a regional effort involving state, local and federal law enforcement agencies to stop illegal ATV and dirt bike riders.

"It's about seven jurisdictions. We're all working together and we've been working together since last year," Lanier said.

"That is troubling, that type of situation, and again, sharing this information is very powerful. We've partnered with law enforcement and others to allow us to do our jobs, basically," Montgomery County Fire and Rescue spokesman Pete Piringer said.

One resident took cellphone video that shows dozens of people riding ATVs and dirt bikes just south of the U.S. Capitol on Sunday night.

"We have a gang of ATV and motorcycle riders blowing through stoplights, completely disregarding the safety of anybody that's walking on the side of the street. There was a Segway tour coming through. There was no respect shown to anybody," said Jeffery Johnston, who shot the video.

Police ask anyone who sees the vehicles – which often zip through streets and sidewalks, sometimes in large groups – to call 202-727-9099 or text 50411 and give a description of the vehicle, its operator and where it was being driven.

"Mini-bikes, dirt bikes, all-terrain vehicles and other motorized bikes and multi-wheeled vehicles pose a danger to pedestrians and other motorists and are illegal to operate on DC's streets," a police flier distributed last year to D.C. residents said.

Fourteen people riding dirt bikes and ATVs were wanted by police in May 2015 in connection with the shooting death of local news reporter Charnice Milton. Milton, 27, was shot and killed on the 2700 block of Good Hope Road SE as she waited for a bus. The shooter was riding a dirt bike and was trying to hit someone in another group of riders, Police Chief Cathy Lanier said.

No one has been charged with her death.