Los Angeles police officers have shot and killed a homeless man during a confrontation on a city street.
Officials said the officers encountered the man while responding to a robbery call.
Local media have quoted police as saying the man was resisting arrest, and tried to grab one of the officers' weapons.
The officer then shot the man.
"During that altercation at least one less-than-lethal device, a taser, was deployed.
"However at this time we still do not know if that taser did strike the suspect. After that the struggle continued and an officer-involved shooting occurred," said Los Angeles Police Department Sergeant Barry Montgomery.
Video of the incident was posted online and shows the officers scuffling with a homeless man.
Once on the ground, the man continues struggling, at which point several shots are fired.
Witnesses gave varying accounts about the shooting, with some saying the man had reached for one of the officer's guns and one saying he heard an officer saying: "He's got my gun".
Other witnesses said the police had used a taser on the man before shooting him.
The incident appears to have happened in an area of downtown Los Angeles known as skid row where homeless people pitch tents at night.
The homeless man in the video was declared dead at a hospital shortly after the shooting, the Los Angeles Times reported, citing police spokesman Sgt Montgomery.
Police could not be reached by Reuters to confirm the report.
The man has not yet been identified.
A series of civilian deaths at the hands of police in the past year has become a touchstone for troubled race relations in the United States, most notably in Ferguson, Missouri, when an unarmed teenager was shot and killed by a police officer, triggering weeks of protests and some rioting.
A grand jury cleared the officer of wrongdoing.
