CHICAGO >> As the video begins, a man in a baseball cap and sweatshirt is on a street, moving in a circle as he talks into a camera he seems to be holding. Suddenly the sounds of pops, one after the next, interrupt. The camera flips to different views, then lands face up, pointed to the sky, as a gunman steps into clear view, still shooting.

It is a jarring, disturbing, highly cinematic video, and the police are trying to determine whether it really is what it looks like: a selfie video that inadvertently recorded the man’s own shooting. Since it emerged Thursday night, the video has taken off on social media.

Anthony Guglielmi, a spokesman for the Chicago police, said the department suspected that the video may have captured a shooting that was known to take place Thursday afternoon along a South Side street — the latest in what has been a gruesome rash of more than 600 shootings in this city this year. But Guglielmi said the department had not verified a link between the video and the shooting, and could not be certain it was legitimate.

A man who was shot was in critical condition, the police said, having been shot four or five times, but they had not yet been able to learn from him whether he was the man in the video. Law enforcement authorities said the wounded man was 30 and a known gang member who had been released from prison not long ago.

Some experts say Chicago’s uptick in shootings and killings may be an anomaly, but it has caused deep concern here. Officials said many of the shootings involved the city’s increasingly splintered web of gangs, with a growing number of disputes now playing out on social media sites — the equivalent of gang graffiti from another era.

Not long after the shooting Thursday, the police said they found the video on Facebook during what has become a routine search of social media in such investigations. As soon as calls of shootings and other violence come in, police analysts begin scanning for related chatter, videos and postings. “That’s in our playbook at this point — we canvass on the street and we canvass digitally,” Guglielmi said.

The rise in violence comes at an especially difficult time: The Police Department is being scrutinized by the Justice Department; a new interim police superintendent took over the department this week; and residents, especially African-Americans, have voiced distrust in the police after the release of a video showing a black teenager named Laquan McDonald being shot 16 times by a white police officer in 2014.

As of Sunday, Chicago had reported 133 murders in 2016, compared with 77 in the first three months of last year. And shootings have increased 91 percent from the same period a year ago.

By Friday afternoon, no arrests had been made in the shooting that took place Thursday. The police said the gunman fled in a vehicle.

The video, which was being shared widely on Facebook and Twitter, remained a puzzle for the authorities. After the camera falls to the ground, pointing up at a blue sky and a stop sign, the apparent gunman can be seen raising a gun right above the camera. Faint music can be heard and people call out about taking the wounded man to a hospital. A woman begins to wail. “No!” she cries out, over and over.

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