In Harvard Square's third robbery in less than two weeks, an unidentified man entered the Papermint store in the Shops By Harvard Yard arcade Saturday afternoon and made off with more than $400.

The suspect, whom police described as a Black male in his 20s, told customers and store employees that he would kill them if they tried to stop him or call the police, Harvard police said yesterday.

The suspect motioned as if he had a gun in his pocket, knocked a female store employee to the ground and then ran off with the all the cash in the register, police said.

Before leaving the store the suspect also ripped the phone from the wall to thwart anyone who might attempt to call for aid, police said.

Store employees were so frightened by the incident that they waited almost 10 minutes before calling the police. By the time authorities had been notified, the suspect had fled in the direction of the Harvard Square T stop and was gone.

Harvard and Cambridge police searched the area but were not able to find the suspect, authorities said. No arrests have been made in the case and the investigation is still ongoing, Harvard Lt. John E. Stanton said yesterday.

Employees of Papermint refused to discuss the incident yesterday.

Harvard police have taken the store's phone andseveral other items into custody and thedepartment's Criminal Investigations Division willdust them for fingerprints today, Stanton said.

Police said the suspect was described as beingabout 5'6", weighed 140 Ibs. and had a round face.

Saturday's crime comes is the wake of two otherrecent robberies in the Harvard Square area.

On Friday, a man robbed the 140 Mt. Auburn St.branch of the Wainwright Bank and Trust Co.,fleeing the scene with about $700 in cash.

Last week, two suspects were shot in broaddaylight in Harvard Square after they and a thirdman attempted to rob an armed guard making adelivery to the Bank of Boston.

Victor T. Chen contributed to the reportingof this story.