LOS ANGELES • San Francisco's police chief resigned on Thursday at the request of the city's mayor, hours after a black woman was fatally shot by an officer.

Mayor Ed Lee announced Police Chief Greg Suhr's resignation at a news conference, saying he hoped to "heal the city" that has been rocked by racial tensions.

"The progress we have made has been meaningful, but it has not been fast enough, and that is why I have asked Chief Suhr for his resignation," Mr Lee told a news conference.

Hours earlier, Chief Suhr had told reporters that a 27-year-old black woman driving a stolen car was shot and killed by police after she ignored orders to stop the vehicle.

The shooting took place amid heightened tensions between San Francisco's police department and African-Americans over a number of racially charged incidents.

The department has also been embroiled in controversy over racist and homophobic text messages exchanged among officers.

"The past several months have shaken and divided our city, and tensions between law enforcement and communities of colour that have simmered for too many years have come into full view," Mr Lee told reporters.

"These shootings, justified or not, have forced our city to open its eyes to questions of when and how police use lethal force," he added.

The mayor said he had appointed Mr Toney Chaplin, a 26-year veteran of the force, as acting police chief, and vowed to continue with reforms.

Activists had been calling for Mr Suhr to step down for months and a group known as the "Frisco Five" had gone on a hunger strike for nearly 17 days to press their demands.

Chief Suhr's departure, which comes days after he pledged not to resign, is the latest in a series of exits of big-city police chiefs who have come under intense pressure during the past year after anger over the deaths of African-Americans at the hands of police officers.

In July, Baltimore police commissioner Anthony Batts was fired when parts of the city erupted in riots after a video emerged of officers arresting a black man who later died of an injury suffered in police custody.

Earlier this month, a senior official at the Los Angeles County Sheriff's Department, chief of staff Tom Angel, resigned following criticism over e-mails he sent disparaging blacks, Muslims, Latinos and women.

AGENCE FRANCE-PRESSE, NEW YORK TIMES