DETROIT -- Assembly lines at factories run by Detroit automakers will come to a halt Friday to commemorate the end of slavery in the U.S. and to support protests after the death of George Floyd.

Work will halt at Ford, General Motors and Fiat Chrysler factories for nearly nine minutes at 8:46 a.m. and p.m. in demonstrations organized by the United Auto Workers union.

"We do this in support of the millions who are demanding an end to racism and hate and calling for real reforms," union President Rory Gamble wrote in a note to the UAW's 400,000 members.

Floyd, who is black, died May 25 pleading for air as a white Minneapolis police officer held a knee to his neck for nearly eight minutes. Minnesota prosecutors acknowledged Wednesday that the officer had his knee on Floyd's neck for 7 minutes, 46 seconds -- not the 8:46 that has become a global symbol of police brutality.

All three automakers have agreed to shut down lines for 8 minutes and 46 seconds on each shift Friday. In addition, all employees at the companies are being asked to be silent for 8:46.

Friday is Juneteenth, considered the oldest known celebration commemorating the end of slavery in the United States.