Debate over the use of force involving deadly weapons and the safeguarding of the public are hot topics nationally. That debate intensified in San Francisco recently.

Guns, shootings, death and protests - those words kept appearing in headlines across the nation since Dec 2 after five police officers fatally shot a man who had allegedly stabbed another man minutes earlier in the city's Bayview neighborhood. He was wielding a large kitchen knife when surrounded by officers.

The confrontation between Mario Woods, 26, and the police was caught in a smartphone video that recorded Woods' last minutes of life on Wednesday.

Officers first shot him with lead-filled beanbags. He fell, got up again and approached an officer, still armed with his knife, which prompted the police to fire live ammunition.

The release of the video and Woods' death have sparked outrage in the city and raised tensions in the black community in the Bay Area. Many community leaders have called for the resignation of San Francisco Police Chief Greg Suhr, arguing that officers were wrong to use deadly force in the incident.

In response to the public outcry, the five officers involved in Woods' death have been placed on leave without pay, pending the Police Department's investigation. There are three investigations underway.

The San Francisco district attorney is probing the incident, too, with a focus on use of force and accountability.

In a statement issued on Tuesday, San Francisco Mayor Ed Lee said he saw the video and "found it very upsetting, as many did".

"We owe all San Francisco, communities of color, and the Woods family, a full and transparent investigation without delay," the mayor said.

Lee reassured city residents that deadly force is always the last resort.

"The men and women of our police department dedicate their lives to protecting people and building trust with the community," Lee said. "They too deserve more alternatives to lethal force in order to best de-escalate conflict."

Lee had directed Suhr to take specific, immediate action to ensure that police officers have more options to resolve situations with the minimum use of force. Since last week, officers already were equipped with protective shields and received instruction for when and how officers use their firearms. The police also will increase mandatory, recurring training on de-escalation skills.

Lee also directed the Police Commission to review all existing policies regarding the use of force to "make it perfectly clear that the department's policy is that using lethal force is the last resort. This might require fundamentally revising the department's policy through general orders and adopting any necessary training or equipment, in addition to what the chief has already instituted."

This country has seen far too many incidents in which conflicts between police and young men of color result in the death of w young person, Lee said.

"In San Francisco, we're not this kind of city. That's not our values. So let me say again very clearly, as I've said before, Black Lives Matter," Lee said in his statement.

Contact the writer at junechang@chinadailyusa.com