A Bay Area Rapit Transit (BART) official revealed that one reason the agency had withheld crime statistics from the public was the fear that the data could lead to criticism of racial minorities.

According to the San Francisco Chronicle, Assistant General Manager Kerry Hamill argued in a July 7 memorandum to BART’s board of directors that the agency wanted to avoid the “disproportionate elevation” of crimes that “unfairly affect and characterize riders of color.” She also reportedly said that criticism of the agency’s decision to withhold crime information was “generated for the benefit of media themselves,” and said that crime on BART was lower than in some of the surrounding communities.

The leaked memorandum will add fuel to public controversy over a slew of mass robberies on BART trains. In April, a group of roughly 60 teenagers swarmed a BART train near the Coliseum station in Oakland and began attacking passengers, robbing them of valuables. BART had surveillance video of the attack but chose not to release it because some of the alleged robbers were reportedly juveniles. In addition, BART chose not to ask the public for help in identifying and catching the robbers until after the crime began receiving media coverage from the Chronicle and other outlets.

Another, similar mass robbery was partially foiled recently by an African-American man who fought the teens and retrieved the phone of a 62-year-old woman who had been beaten.

In the absence of information, speculation has begun to increase online that the alleged perpetrators were black, and that authorities were trying to avoid an uncomfortable discussion about race. “BART has been flooded with a slew of racist emails and phone calls suggesting the high-profile robberies were the work of young African Americans,” the Chronicle notes.

Since May, the Chronicle notes, BART has stopped providing a daily log of reported crimes and now uses an online mapping system that critics claim is opaque.

Racial tensions have increased in the Bay Area recently, thanks in part to growing gentrification that has seen tech wealth buy out residents of formerly black neighborhoods, and also due to community concerns about policing that have fueled the the Black Lives Matter movement.

On New Year’s Day 2009, a young black man named Oscar Grant was shot and killed by a BART police officer, who was later convicted of involuntary manslaughter.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named one of the “most influential” people in news media in 2016. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.