3D-printed models of people are seen in front of a Facebook logo in this photo illustration taken June 9, 2016. REUTERS/Dado Ruvic/Illustration

By Justin Madden

CHICAGO (Reuters) - A Chicago man was shot and killed while live streaming a video on Facebook, police said on Friday, just days after a double-homicide in France in which the killer later took to Facebook Live to encourage more violence.

Antonio Perkins, 28, was found face down on Wednesday night in a vacant lot with gunshot wounds to the neck and head on the city's west side, Chicago police officer Laura Amezaga said.

Perkins was taken to a hospital where he was pronounced dead. Police on Friday identified the man in the video as Perkins, who they said was a documented gang member. No arrests have been made.

In France, a 25-year-old man killed a French police commander and the commander's partner on Tuesday, then he took to Facebook Live with a 12-minute video encouraging followers to kill prison staff, police officials, journalists and lawmakers.

The incidents underscore the immense challenges companies such as Facebook Inc , Twitter Inc and Google's YouTube face as they push live video streaming to hundreds of millions of people.

Facebook in recent months has made its Live feature - which allows anyone to broadcast a video in real time - a central component of its strategy. It allows people to stream from their smartphone.

Chicago, the third-largest U.S. city, has drawn attention due to its gun violence, which police have blamed largely on gang violence and a proliferation of stolen guns. There were nearly 500 homicides last year, and gun violence is up in 2016, police say.

The Facebook Live video appears to show Perkins recording himself and a group of people in front of a row of homes before someone opened fire. The phone appears to tumble through bloody grass before going black. The audio continues with bystanders screaming and crying.

The video remains on Facebook with a user warning message about its graphic nature.

A spokeswoman from Facebook acknowledged the video posting, saying it does not violate company policy. The social media site will remove a video if it celebrates or glorifies violence, she said.

(Reporting by Justin Madden; Editing by Daniel Trotta and Alan Crosby)