Sgt. John O'Brien looks at an intersection in Montgomery County where he said his crash investigators were nearly run over early Sunday morning. (Dan Morse/The Washington Post)

The weekend, the holiday, and a host of bars and restaurants along a busy stretch of road.

Just the mix, police say, that draws drunk drivers.

But few officers had ever seen a sequence of events, starting at 11:14 p.m. Saturday, quite like what unfolded along Rockville Pike, just north of the District in Montgomery County.

It began with a man driving a BMW. For reasons still unclear, his car and a scooter collided, killing the scooter driver. The BMW driver ran off, authorities said, but was found a short time later by officers.

As officers then worked that crash scene on the road, a blue Mazda approached. Its driver stopped at a closed-off intersection at the investigation site but didn’t move for several minutes. The lag attracted the attention of several nearby officers, who walked up to the car — and said later that they detected the smell of alcohol — and detained that driver.

On left, Intersection of Rockville Pike and Congressional Lane, where a fatal crash started a series of three DUI-related investigations. On right: Detectives say the surviving driver in the fatal wreck drove down this portion of Congressional Lane, stopped his BMW, and fled on foot. (Dan Morse/The Washington Post)

Lastly, at 3:51 a.m., as investigators were still at the scene of the crash that included the scooter, a 20-year-old driver drove up, seemingly oblivious to bright-orange traffic cones and a large truck bearing a “road closed” sign. That driver drove around and over the cones — sending investigators bailing for cover, police would later say in citing her.

All three drivers, officials said Tuesday, were legally drunk. The final driver had a blood alcohol level of 0.18, according to police officials, more than two times the legal limit.

“It makes you wonder,” said Montgomery County Police Sgt. John O’Brien, who pursued the third driver and pulled her over, “what was taking place in the rest of the county during those hours.”

Maybe not exactly what was happening on Rockville Pike at Congressional Lane, but perhaps something close, given recent arrest numbers.

As of Tuesday, the county’s annual Alcohol Holiday Task Force had made 150 arrests over the previous five weeks for drivers suspected of being under the influence of alcohol, drugs or both. Police officials noted that the tally comes only from the task force officers and does not include DUI arrests made by officers doing regular patrol work.

The events Saturday started with two drivers going in opposite directions.

In the northbound lane of Rockville Pike, Mark Steven Andrade, 24, prepared to make a left onto Congressional Lane in a 2008 BMW 335xi, according to a police account. In the southbound lane, Ross Stanley Redler, 56, was riding a 2014 TaoTao Scooter.

“For reasons still under investigation,” O’Brien said, “the two vehicles collided.”

Redler was taken to a hospital, where he died.

Andrade ran from his car after the crash but was found by officers a short time later along Congressional Lane, according to police officials. Officers took him into custody on suspicion of drunken driving while the collision remains under investigation.

His lawyer, David Felsen, said Tuesday that he has emailed the police, offering help in their crash review.

“There are substantial questions as to whether the allegations of my client’s drinking had anything to do with the collision,” Felsen added.

He said Andrade has a speeding conviction from two years ago but no criminal record.

“Any accident of this nature is painful for all those involved, regardless of fault,” Felsen said.

In Montgomery County, after fatal wrecks, investigators from a Collision Reconstruction Unit spend hours at the crash scene — taking measurements; examining damage to cars, signs and roads; and taking photographs. That is what they started doing on Rockville Pike after the car-scooter crash.

Signs and flashing lights were set up to signal closed-off lanes. Officers worked the edges of the scene to help direct motorists and keep the scene clear.

At 1:50 a.m., a blue Mazda, heading south on Rockville Pike, stopped at Templeton Place.

“It should be noted,” Rockville City police officers would later write, “that the intersection was being blocked by two marked cruisers with all their emergency lights activated and two uniformed officers in reflective traffic control vests standing in the middle of the intersection, directing approaching vehicles to turn around.”

An officer approached the Mazda, smelled alcohol and saw that the driver was having trouble finding his driver’s license in his wallet, before asking the driver how much he’d had to drink, according to the police report.

“About two drinks,” the driver said, according to the police report, which said the officer asked: What does “about two drinks mean?”

“I guess it depends how strong my friend mixed them,” the driver answered, the police report states.

The driver, Philip Michael Murray, 27, of Rockville, was taken into custody and tested to have a blood alcohol level of 0.12, according to Rockville police.

Murray declined to comment Tuesday.

The Collision Reconstruction Team was still working at 3:51 a.m. when Taylor Leigh Stevens, 20, of Rockville, was heading south on Rockville Pike at the wheel of a Hyundai sedan. She didn’t stop at the signaled road closure, a police spokesman said, and “drove past a State Highway Administration dump truck that was parked in the road and was displaying flashing lights and ‘Road Closed’ signs.”

The crash reconstruction detectives heard the car as it ran through traffic cones. They tried to get the driver to stop, with one waving a flashlight, the police spokesman said.

But the sedan kept going, according to authorities, so investigators jumped out of the way. After the car drove all the way through the scene, O’Brien pursued the car and pulled it over.

Stevens was cited for a series of traffic infractions, including driving under the influence.

She could not be reached for comment Tuesday.