Tulsa Mayor G.T. Bynum on Tuesday announced plans to re-investigate whether there are mass graves in the city from a 1921 race massacre believed to have left hundreds of African-American citizens dead. “We owe it to the community to know if there are mass graves in our city. We owe it to the victims and their family members. We will do everything we can to find out what happened in 1921,” Bynum was quoted as saying by The Washington Post. City authorities plan to work with the Oklahoma Archaeological Survey or the Arkansas Archaeological Survey to conduct the investigation, Bynum said. The city’s Oaklawn Cemetery is seen as the “most likely” place where mass graves would be found, he said, with a “giant grassy area” behind all the headstones in question. The 1921 massacre was one of the horrific cases of racial violence in U.S. history but didn’t get much attention until historical accounts from the 1980s began to shed details on the bloodshed. More than 300 black residents are believed to have been murdered after a white mob stormed a neighborhood in the city known as Black Wall Street at the time. Eyewitness accounts of the rampage said many of the victims had been tossed into mass graves. An earlier investigation into the mass graves was inconclusive.