Two men are at large after robbing a group of University employees at gunpoint outside Mather House last Thursday night, police said.

The men approached three staff members, whose names authorities would not release, in front of the Mather House gate at 9:55 p.m. as they sat in their car with the motor running.

Cambridge Police Department (CPD) Sergeant Lester J. Sullivan said one of the robbers barked "give me all your money" as he stuck a small black handgun through the window. The victims complied, handing over pagers, keys and wallets containing credit cards and $150 in cash.

The robbers then fled the scene, running down Cowperthwaite Street and then taking a right onto Banks Street before the victims lost sight of them.

Both CPD and Harvard University Police Department (HUPD) officers responded to the site of the robbery. Ten to 15 cruisers were present at the peak of police activity, according to Dr. Cheng-San "Louie" Chen, who saw the police response from his shop, Louie's Superette, which is located near the crime scene.

According to the authorities, the suspects are two black youths, 17 to 20 years old. The victims described the robber with the gun as a 5'8, dark-skinned male, with a muscular build, a round face and large teeth. He wore a dark-colored bandana, a dark plaid shirt, a black leather jacket and blue jeans.

The second suspect was described as a dark-skinned male, about six feet tall with a thin build. He wore a dark-colored waist length jacket and blue jeans.

The Mather tower is being used to house students working for several college-sponsored projects this summer, including Project Health, a community service program affiliated with Boston Medical Center.

Summer residents said they were disturbed by the incident.

"After the robbery I definitely made sure to have someone always walk me back ... to Mather every night," summer Mather resident Roxanna N. Curto '00 wrote in an e-mail message.

HUPD did not issue a community advisory about the incident until this Wednesday because of a problem with their e-mail distribution lists, according to HUPD spokesperson Peggy A. McNamara.

Students living in Mather said they were upset by the low publicity the crime received--some were unaware that a robbery had taken place until days after the incident.

"I was glad to see the posters," wrote Mather resident Brandon K. Walston '01 in an e-mail message. "However, I just wish that they'd been put up sooner--the day following the actual robbery rather than almost a week afterwards."

Eun Soo Kwak '02, campus coordinator for Project Heath, said that she felt the delay in warning students about the robbery was symptomatic of what she perceives as Harvard's generally neglectful attitude towards summer programs.

"The fact that they didn't tell us about the incident right away speaks to the general level of treatment that we get during the summer," she said.

The HUPD Criminal Investigation Unit is working with a case investigator from CPD on the matter.

A police investigation of this kind involves basic detective work, said CPD's Sullivan.

"We'll bring the victims in to view photos and see if they can identify perpetrators, examine to see if there's any physical evidence at the scene, interview any witnesses that may have observed anything," Sullivan said.

Sullivan said the investigation will take between a few days and several weeks, depending on the kind of evidence that is found.

Last week's incident is the third reported armed robbery on campus this year. Two others took place on the evening of February 22 when a group of four teenagers went on an evening crime spree, robbing two undergraduates at gunpoint before committing two more robberies in Cambridge.

The suspects were never caught and the case was closed without a finding.

McNamara said that though there is no reason to think the June 6 incident is related to the previous two robberies, investigators are examining all leads.