Drivers across the city are being urged to take extra precautions in the wake of a series of carjackings, some of them armed, in Brooklyn and Staten Island that detectives believe may be part of a pattern.

Police say seven carjackings involving luxury cars like Mercedes, BMWs and Range Rovers were reported in May, amounting to about two per week for that month. All of the cars were stolen after 11 p.m., and police believe the same suspects are behind some of the thefts.

All of the seven cases involve one to three carjackers; in three cases, a suspect uses either a gun or a knife and another threatens the victim.

In two of the carjackings, the suspects use their car -- also a high-end model -- to bump the victim's car, and then steal the victim's car when the person gets out to assess the damage. 

Another victim was carjacked while waiting at a car wash. 

Two of the stolen cars have been recovered in Newark, N.J., and another was found by Border Enforcement Security officials inside a container en route to Togo, Africa.

Anyone with information about the carjackings is asked to call NYPD Central Robbery Division at (212) 426-2723 or the NYPD Staten Island Robbery Squad at (718) 876-8414. 

Tips can also be submitted on the NYPD Crime Stoppers website.