Police in the District and Montgomery County say they suspect the same pair of armed robbers may be responsible for a spate of at least 10 street robberies since late November in Upper Northwest and within blocks of the Bethesda-District line near Western Avenue.

The most recent that appears related, said District police, occurred Tuesday at about 9:20 p.m. when a woman walking in the 4100 block of Livingston Street NW was robbed at gunpoint of her purse and cell phone.

The woman told police she had noticed a man hiding in the tree line on the south side of the street. When she tried to cross the street to avoid him, she told police, the suspect ran up to her and held her up.

The robberies are not like the grabs that targeted iPhones and cellphones last year, according to police. The suspects in the recent events usually show guns and have taken purses, briefcases and wallets in the robberies, police said,

Cmdr. George Kucik, head of the Criminal Investigations Division for the District police, said “we can’t say definitely these are all the same suspects because no one has been caught, but there are enough similarities that we are looking on them as linked.” Capt. David Falcinelli, commander of the Bethesda district for Montgomery County, said two robberies on Nov. 22 and Dec. 26 near the Bethesda border with the District also are believed part of a pattern.

The Livingston Street robbery comes in the wake of three similar stick-ups within 30 minutes on Sunday in the early evening in Cleveland Park and Friendship Heights. District police say they believe another four since Dec.10 also share similar characteristics.

The robbers generally have hit in the early evening hours between 6 p.m. and 11 p.m, according to police. They have usually approached people who are alone and walking or exiting a car, although there have been incidents in which two people together were robbed.

Victims often have been taken from surprised and sometimes approached from behind and descriptions of suspects have been fragmentary. “This probably doesn’t take more than 30 seconds and the victims have been caught by surprise,” said Kucik.

The information victims could provide have police looking for two black men, both about 6-feet-tall and in their 20s to 30s who mask their faces either with a scarf or with the hood of their jackets. The suspects have shown guns in the District incidents, District police say. A gun was shown in at least one of the Bethesda robberies, Falcinelli said.

The robbers usually tell their victims to walk in one direction while they flee in the other, said police. Kucik said they suspect there is an escape vehicle nearby, and have one report of a dark blue car being involved. “But we know people often use stolen cars and switch them out once they get too hot,” Kucik said.

The two police departments say they have ramped up the visible police presence on patrol but also have taken more covert steps that they declined to detail using tactical officers in the area.

Kucik said police urge anyone who is approached “to cooperate. No one has been injured thus far and we do not want to see that happen.”

He said police also are asking residents to be aware of their surroundings and to call police if they see a car or activity that seems suspicious. “Maybe it’s innocent but we would rather make contact with a person and find out there is a legitimate reason for them to be in an area, “ Kucik said.

D.C. Council member Mary Cheh (D-Ward3) and police officials are planning to discuss the robberies at a community meeting scheduled for 8 p.m. Thursday at St. Mary Armenian Church at 4125 Fessenden St., according to Kiara Pesante, a spokeswoman for Cheh.