To the Volvo’s driver, it began as a jolt from behind just north of Potomac. He got out to speak with the driver who rear-ended him and check on the damage.

But two masked men — one armed with a gun, the other a knife — beat him, wrapped his ankles and wrists in duct tape and forced him into his own trunk. Then they drove him to several ATMs, took money from his accounts, and left him in a church parking lot.

Montgomery County police said Monday that the robbers may have tried the gambit at least once before. They are looking for suspects but have no descriptions of the men. Detectives described their vehicle as a white or light-colored truck or sport-utility vehicle with Maryland license plates.

In the meantime, police are warning motorists not to exit their cars after relatively minor collisions, particularly in dark areas. When in doubt, said Capt. Paul Starks, a police spokesman, call 911 to let everyone know you are not fleeing the accident, and arrange to meet officers at a better-lighted place, such as a gas station or convenience store.

“If you think these folks are possibly setting you up, listen to your gut. Listen to your instincts,” Starks said. “Make sure you’re safe before you get out.”

The most recent incident happened about 12:20 a.m. Saturday, as a 58-year-old man was driving along Jones Lane near Carry Back Drive, about 10 miles northwest of where Interstate 270 and the Capital Beltway merge.

Eleven days earlier, shortly before midnight on April 3, a 49-year-old woman driving her Range Rover along Jones Lane passed a parked car near Carry Back Drive, she said in an interview Monday. The vehicle then came up quickly from behind.

“I was blinded by the lights in my rearview mirror,” she said.

The vehicle then struck her SUV from behind, according to the woman and police.

The woman immediately called 911 but did not stop her SUV, according to the victim and authorities. After seeing the woman on the phone, the other driver made a quick U-turn and drove away, police said.

The woman said that while she was on the phone with the 911 operator, she said she had been followed and intentionally hit but was advised to get out of her vehicle and exchange information with the other driver.

“What are you, crazy?” the woman said she asked the 911 operator.

Starks, the police spokesman, said the department will review the 911 recordings to understand what was said.

“We’re concerned about some of the questions and concerns she has brought up,” Starks said. “From the beginning, this woman did the right things.”

The woman said she heard Monday morning from detectives who were looking into similarities between the Saturday-morning incident and hers. They told her that the man in the more recent incident had been badly beaten.

“That could have been me,” she said. “I could have been killed.”

Starks said that ramming-type robberies are rare, particularly in Montgomery. Still, he said, stopping along a darkened road can be dangerous simply because of the risk of being hurt again — by another car.