A sudden wave of street robberies has caused concern in the past month in the Capitol Hill area around Eastern Market.

In a 30-day stretch that ended this week, 15 robberies not involving weapons were reported in the police patrol area that includes the market and the nearby Metro station. In the same period a year ago, the number was one.

After a robbery was reported about noon Dec. 19 on Eighth Street SE, a commercial strip, a post on an e-mail group said the outbreak was “becoming absurd.” Police said half of the robberies involved the theft of smartphones or other cellphones that were snatched from the victims.

Police said that many of the incidents occurred between the hours of 8 p.m. and midnight and that Fridays accounted for 43 percent of them. Police said they are aware of the problem and are doing everything they can.

On Thursday, three robbers, one with a gun, held up a Radio Shack store near the Metro station. Unlike the recent street robberies, a weapon was used, but what was taken was similar: electronic equipment.