A 23-year-old female Metrobus driver was forced to perform a sexual act after two men forced her at gun-point to drive her empty bus about three miles across the city Sunday night, District police said yesterday.

Police said the incident occurred about 9 p.m. when the driver was changing signs on her bus at the end of a run. Two men, one armed with a gun, boarded the bus and forced the woman to drive to the 400 block of F street NW. There the men ordered her to the back of the bus where she was forced into a sexual act with one of the men, police said.

The two men fled after taking $32 from the driver's purse. The woman was treated at Washington Hospital Center and released. Police said there are no suspects in the case.

Police said the attackers seemed aware of the bus alarm systems, designed to alert Metro headquarters, and ordered the woman not to activate them.

The rape of a female bus driver last May touched off a one-day walkout by bus drivers seeking more protection. Metro and Washington police have since increased their surveillance and undercover work, and Metro has equipped its 1,800 buses with silent alarms.

George Davis, president of the Amalgamated Transit Union Local 689 which represents some 3,000 Metro bus drivers, said yesterday that the drivers have been getting "exceptional" efforts from Metro and Washington police.

District of Columbia City Councilman Jerry A. Moore Jr. (R-At Large, however, called Sunday night's attack "a very shocking incident" and said yesterday that he would investigate it himself to be sure Metrobus drivers are getting sufficient protection. Moore is chairman of the Council's Transportation and Environmental Affairs committee.