The St Louis County police department has moved in riot squad officers as crowds have gathered to witness the scene where a black teenager has been shot dead by police in the town of Berkeley, Missouri.

At 0947 GMT, St Louis Police department moved in officers armed with riot squad apparel, including shields, batons and helmets.

The police have not yet asked crowds to move away from the scene. The image above is taken from the live video stream from user Stackizshort on Ustream.

The shooting

The victim has been identified as 18-year-old Antonio Martin and the incident took place near the flashpoint town of Ferguson where teenager Michael Brown was killed by officer Darren Wilson earlier this year.

The teen was reportedly killed outside the Mobil gas station in the town and social media users posted photos and footage of Martin's mother at the scene.

Initial reports from witnesses suggest that Martin was unarmed while others claim that a gun was found at the scene. Whether Martin was armed or not at the time of the incident could be immediately verified.