PROTESTERS HAVE SET fire to a police station during the third night of protests in Minneapolis over the death of a black man after a police officer knelt on his throat.

A Minneapolis Police Department spokesman said the protesters broke into the 3rd precinct station, which has become the scene of numerous demonstrations by those angered at a video showing 46-year-old George Floyd’s arrest.

The spokesman said police abandoned the building “in the interest of the safety of our personnel” while livestream video showed the protesters breaking in, setting the building ablaze and igniting fireworks as fire alarms blared and sprinklers ran.

The demonstrations began on Tuesday after Floyd died the previous day.

A video in which officer Derek Chauvin, who is white, kneels on his neck until he slowly stops talking and moving later went viral.

Chauvin, whose driveway was splattered with red paint and the graffiti “murderer”, has not spoken publicly since Floyd’s death. He and the three other officers involved in Floyd’s arrest were fired on Tuesday.

Donald Trump accused the protesters of besmirching Floyd’s memory, hitting out at the city’s over his response to the protests in a series of tweets.

“I can’t stand back and watch this happen to a great American city, Minneapolis. A total lack of leadership,” he said.

“Either the very weak radical left Mayor, Jacob Frey, get his act together and bring the city under control, or I will send in the National Guard and get the job done right.

“These thugs are dishonoring the memory of George Floyd, and I won’t let that happen. Just spoke to Governor Tim Walz and told him that the military is with him all the way.

“Any difficulty and we will assume control but, when the looting starts, the shooting starts.”

Walz had called in the National Guard at the Minneapolis mayor’s request earlier on Thursday, but it was not immediately clear when and where the reserve force was being deployed and troops were not seen at protests in the city or nearby St Paul.

Businesses in both cities have boarded up their windows and doors in an effort to prevent looting, and the city has also shut down nearly its entire light-rail system and all bus services until at least Sunday.

Meanwhile, Minneapolis City Council records showed that Chauvin moonlighted as a bouncer at a downtown Latin nightclub and was among a group of six officers who opened fire on a stabbing suspect in 2006 after a chase that ended when the suspect pointed a sawn-off shotgun at them.

The suspect, Wayne Reyes, was hit multiple times and died, and a grand jury decided the use of force was justified.

Two years later, Chauvin shot Ira Latrell Toles as he was responding to a domestic dispute.

Online city records also showed that 17 complaints have been filed against Chauvin during his 19-year service.

Sixteen complaints were closed with no discipline, and the remaining complaint generated two letters of reprimand, with one apparently related to the use of a squad car dashboard camera.

The records do not include any details on the substance of the complaints.