Video shows officer fatally shooting man outside California 7-Eleven (Warning: GRAPHIC)

HUNTINGTON BEACH, Calif. – Videos posted on Twitter Friday morning show a Southern California police officer struggling with and then shooting a man who collapses in front of a 7-Eleven.

Police say the man was hospitalized and later died.

A 17-second video of the incident was initially posted to Twitter just after 9:30 a.m. It shows a Huntington Beach officer firing multiple times at a man, who falls to the sidewalk.

A Huntington Beach Police Department spokeswoman said the officer contacted a male individual outside the 7-Eleven at 6012 Edinger Ave. and they "got into an altercation." Then an officer-involved shooting occurred and the male was taken to a hospital with unknown injuries, police spokeswoman Officer Angie Bennett said.

Police weren't immediately releasing any other details, but, just after noon, Bennett confirmed the man had died. His identity has not been released.

A few additional seconds of video captured by the same photographer who tweeted the shooting footage appear to show the officer struggling with the man, whose back is on the pavement. The man appears to take something off the officer's duty belt before the officer pulls away and fires his weapon.

The additional video was distributed to local television news stations by a freelance news photographer, who also tweeted the footage.

Two witnesses who were separately going to the 7-Eleven described the events. Both witnesses – neither of whom wanted to be identified – said the officer approached the man, who then swung a punch toward the officer. One of the witnesses said the man "hit" the officer, while the other said the man "tried to throw a punch."

Then the man and the officer were on the ground wrestling when the man grabbed what appeared to be the officer's "magazine clip," both witnesses said.

In the video showing the gunfire, the man, clad in dark pants and sweatshirt, is clearly holding something in his right hand before the shots are fired, causing him to convulse and stumble.

It was not immediately clear if the officer fired live ammunition or nonlethal rounds. When asked about this, Bennett repeatedly responded that the shooting was "an OIS" -- officer-involved shooting.

In the video, six shots are fired and then someone yells something that sounds like "Get down, get down." Then a seventh shot is fired and the man stumbles backward and collapses on his side.

The officer picks up a radio and speaks into it, but it's not clear what he says.

A female employee inside the store was grazed by a bullet, one of the witnesses said.

Marina High School, at 15871 Springdale St. and diagonally across Edinger Avenue from the 7-Eleven, was placed on lockdown. The school tweeted that there were many police patrol cars on scene and that students were safe.

Some students said they left school after the lockdown was lifted, too disturbed by the shooting to return to class.

"That was actually basically seeing a person die. It's not like the movies," said student Carmella Marshall. "It's really real."