Here is what you need to know about MS-13, a street gang with an international reach. (Claritza Jimenez/The Washington Post)

An 18-year-old man has been arrested in a series of what police describe as random robberies and assaults in Northwest Washington this week that might be linked to the MS-13 gang.

In one case, the suspect and others possibly linked to the case identified themselves as affiliated with the gang Mara Salvatrucha, which in the Washington area has been mostly active in the suburbs, according to a statement from D.C. police.

Federal law enforcement officials have said MS-13 — considered one of the most dangerous groups linked to murders, prostitution and drug trafficking — has begun to reassert itself after years of relative quiet.

D.C. police charged Christian Mendoza of Northwest with two counts of robbery, two counts of assault with intent to kill and two counts of assault with a dangerous weapon.

The incidents earlier this week in the District occurred over several hours, from 11:30 p.m. Monday through 12:30 p.m. Tuesday. The attacks were in the neighborhoods of Mount Pleasant, Columbia Heights and Adams Morgan.

Police said the first incident occurred about 11:30 p.m. Monday in the 3100 block of 16th Street NW. Police responded to a call about a fight and said they found a person inside a car suffering from a stab wound. The victim told police they had been robbed by several men.

About 1:10 a.m. Tuesday, police said, the suspect hit a man in the head with a rock and stabbed him in the back in the 1700 block of Columbia Road NW in Adams Morgan. Police said the suspect fled on a bicycle.

At 2:45 p.m., police said, the suspect and others approached a young man on a bicycle and asked whether he was a member of MS-13. Police said Mendoza and others — all armed with knives — chased the victim and that one of the assailants stabbed him.

The last assault occurred about 12:30 p.m., when police said Mendoza and another young man robbed a person of a bicycle at knife point in the 2900 block of Sherman Avenue NW. In that case, police said in a statement, Mendoza and his friend “identified themselves as Mara Salvatrucha and questioned the victim.”