SWORDS (Special Weapons Observation Reconnaissance Detection Systems) robots are equipped with either the M249, machine gun which fires 5.56-millimeter rounds at 750 rounds per minute or the M240, which fires 7.62-millimeter rounds at up to 1,000 per minute.
They are still connected by radio to a human operator who verifies that a suitable target is within sight and orders it to fire. Then the robot has the job of making sure lots of bullets are sent towards the target.
The bots are modified Talon robots that have been used by the military for at least four years, but apparently they are better at shooting than human soldiers.
Later the US plans to replace the control system of the bots with a "Gameboy" type of controller hooked up to virtual reality goggles. There are some pictures here. µ