Motorists robbed at gunpoint on Highway 1 near Half Moon Bay

Police tape stretches across a section of street by Northern Arizona University campus in Flagstaff, Ariz., Friday, Oct. 9, 2015, after an early morning fight between two groups of college students escalated into gunfire leaving one person dead and three others wounded, authorities said. (Michael Schennum/The Arizona Republic via AP) MARICOPA COUNTY OUT; MAGS OUT; NO SALES; MANDATORY CREDIT less Police tape stretches across a section of street by Northern Arizona University campus in Flagstaff, Ariz., Friday, Oct. 9, 2015, after an early morning fight between two groups of college students escalated ... more Photo: Michael Schennum, Associated Press Photo: Michael Schennum, Associated Press Image 1 of / 1 Caption Close Motorists robbed at gunpoint on Highway 1 near Half Moon Bay 1 / 1 Back to Gallery

A man and woman were robbed at gunpoint on Highway 1 in San Mateo County on Sunday night after pulling over to let a car that had been tailgating them pass, authorities said.

When the woman pulled over between Half Moon Bay and San Gregorio about 9:30 p.m., the car cut in front of them and stopped suddenly, said San Mateo County Sheriff’s Office spokesman Sal Zuno.

Two men came out of the back of the car: one holding a handgun, the other a knife. Both wore a mask and gloves and forced the victims to lower the windows, Zuno said.

One of the men held a gun to the woman’s head, demanding her purse and cell phone.

The knife-wielding man held the blade against the passenger’s neck and ordered him to hand over his wallet and phone, Zuno said. After robbing them, the men ran back to their car and continued south on Highway 1.

The passenger received minor scrapes from the knife, Zuno said.

The robbers’ car was described as a black Crown Victoria with tinted windows and no license plates. Anyone with more information is asked to call the San Mateo County Sheriff’s Office at (650) 363-4911 or the anonymous tip line at (800) 547-2700.

Jenna Lyons is a San Francisco Chronicle staff writer. E-mail: jlyons@sfchronicle.com Twitter: @JennaJourno