A new covert squad of undercover detectives targeting robberies in the District made more than 20 arrests and confiscated 11 guns in two patrol districts in the past eight days, the department said Wednesday.

D.C. Police Chief Cathy L. Lanier discussed the initiative, called the Robbery Intervention Program, Tuesday on her monthly call-in show on NewsChannel 8. On Wednesday, she published a letter to residents on community Internet boards.

The officers are currently working in the Sixth and Seventh police districts, south of the Anacostia River, where the spike in armed and unarmed robberies are the most pronounced in the city. Police have said increased robberies are a problem across the District.

Lanier said the detectives are targeting areas most likely to be hit and looking at patterns to determine when and where to hide out. In some cases, the chief said on NewsChannel 8, police identified potential robbers before they attacked, seizing weapons, ski masks and stolen cars.

In her note to residents, Lanier said that some people were arrested before they were able to rob someone. They were charged with a variety of other offenses, including outstanding arrest warrants, carjackings, assaults and illegal guns, the chief said.

“It is evident that these suspects likely had intentions to victimize others if it were not for our intervention,” Lanier write.

Robberies spiked sharply, 46 percent, in the first two months of the year, compared to the same period in 2011, according to police statistics. Authorities have said the pace slowed in recent months, though the numbers remain up about 9 percent this year.

Armed robberies continue to be an issue, with 872 reported in the city this year, up 20 percent from the 725 at this time last year. Robberies involving guns have gone up in both the Sixth and Seventh police districts — 24 and 40 percent respectfully.