A middle-aged man slipped a teller a note that said he had a gun and then made off with an undisclosed amount of cash from a Harvard Square bank Tuesday afternoon, police said.

Leona Davidson, at the Cambridge Savings Bank, 1375 Mass. Ave., told police that a man in his thirties walked into the bank at about 3:15 p.m. Tuesday and handed her a note that read, "I have a gun, give me 20's. 100's and 50's."

Bank officials yesterday confirmed that the branch had been robbed, but would not disclose how much money the bandit took.

"We can't really make a comment except that yes, there was a robbery. "Peter A. Rattigan, the assistant treasurer of the branch across the street from Harvard Yard, said yesterday.

Lt. Timothy J. Toomey of the Cambridge Police said yesterday that detectives are pursuing leads and have a suspect in the case.

Toomey added that Cambridge Police are cooperating with the Federal Bureau of Investigation.

The teller described the suspect as a white male in his thirties, five feet, nine inches tall, medium weight, with brown hair and brown eyes.

Other incidents reported to Cambridge and Harvard University Police during the period from March 9 to 15 include.

Fire, Vandals Hit Science Center: Authorities are investigating a fire that broke out early Monday morning at the Science Center loading dock.

The blaze, which Fire Department officials labelled suspicious started in a stack of computer printout paper inside the building near the loading platform at about 2:30 a.m., police said.

Ronald R. Vanelli, the director of the Science Center, said yesterday that the fire, which firefighters said set off the sprinkler system, did not cause any damage.

Cambridge firefighters extinguished the fire in a matter minutes, Lt. Michael R. Travers of the Cambridge Fire Department, said yesterday.

Travers said the cause of the blaze is still under investigation.

Police reported they were called to the Science Center a few moments before that fire is believed to have started on a report of vandalism. Police reported that someone had tried to tear down on of the basement mens' room stall doors.

Computer Stolen: A desktop computer valued at $6.000 was reported stolen last weekend from the Office of Financial Systems (OFS) at Holyoke Center, police said.

E. Lyndon Tefft, the director of OFS, said the computer was used for financial planning and that no computer files containing data had been stolen.

Harvard Police said that a Holyoke Center door on Mass. Ave, had been forced open and burglar alarm wires cut. No other items were reported stolen from the building.

Tefft said the I.B.M. personal computer was in a secretarial area on the third floor. About eight people in the office used it regularly, he added.

Handbag, Cash Stolen: A victim told police her blue leather handbag containing credit cards and $115 in cash was taken from a Boylston Hall office last Friday around 3:30 p.m.

Bicycle Thefts: Three bicycles ranging in value from $101 to $360 were reported stolen from Harvard buildings last week.

A men's 12-speed bicycle was reported taken from the basement of Quincy House D. entry, a Fuji 10-speed mens' bicycle was missing from the foyer of the Weld Boathouse, and a womens' 10-speed was reported stolen from the basement of Weld Hall.

Wallet Lifted: A victim told police that her gold leather wallet containing $25 was taken from her backpack unattended on a shelf in a Byerly Hall room between 4:15 and 4:54 p.m. last Friday.

The thefts were among 10 of less than $100 and eight of more than $100 reported to Harvard police during the week ending Thursday.

University Police also warned seven people off Harvard property and arrested Donald P. Guertin, 34, on address given, for allegedly trespassing at the Science Center Wednesday after having been told to leave Harvard property previously, officers said.