A Tulsa Race Massacre anniversary event in Oklahoma, featuring John Legend and Stacey Abrams, has been unexpectedly cancelled.

The Ordinary People hitmaker and the politician were booked to appear at the nationally-televised event Remember & Rise, in honor of the 100th anniversary of the Tulsa Race Massacre, on Monday, but now the televised gig has been axed due to "unexpected circumstances", according to theGrio.

A statement from officials at the Tulsa Race Massacre Centennial Commission read: "Due to unexpected circumstances with entertainers and speakers, the Centennial Commission is unable to fulfill our high expectations for Monday afternoon's commemoration event and has determined not to move forward with the event at this time. We have hopes to reschedule later in this 100th commemorative year."

The Tulsa Race Massacre, which occurred from 31 May to 1 June 1921, is remembered as one of the worst incidents of racially motivated violence in American history - with Black-owned businesses and homes burned in the Greenwood District of Tulsa.

A 2001 state commission was able to confirm 39 dead, but estimated 75 to 300 people may have died in the violence.

America's Department of Homeland Security officials had indicated fears that the event could be targeted by "violent extremist-white supremacists" but it is not known if this is the reason for the concert's cancellation.