Demonstrators have broken into a Minneapolis police headquarters, setting fires and destroying everything in sight amid unrest unleashed by the killing of a local black man at the hands of law enforcement.

The Minneapolis Police Department's 3rd precinct headquarters was breached late on Thursday night, with a raucous crowd of protesters seen filing into the building, smashing windows and some attempting to set it ablaze.

While the police presence in the area was heavy earlier in the day, it appears officers have since retreated, putting up no resistance to the break-in.

RT's Sophia Narwitz is now at the scene around the precinct, where fire alarms and sprinkler systems were activated amid the mayhem as protesters continued to gather outside.

Following the breach, a police statement said the building had been evacuated "in the interest of the safety of our personnel," while a local reporter with the Star Tribune relayed a law enforcement broadcast warning that "the 3rd Precinct has been compromised" - presumably heard over a police scanner.

The four police officers implicated in the killing of George Floyd on Monday reportedly worked at the 3rd precinct, where protests first escalated earlier this week, descending into riots on Wednesday night.

Looting, arson, and vandalism have been widespread across Minnesota's Twin Cities since, as police further lost control of the situation. While National Guard units were activated by the state government earlier on Thursday, it remains unclear when they will be deployed.