Racist SMS messages referencing slavery have been sent to African Americans across the U.S.—men, women, students, and even high schoolers—with the FBI and other relevant agencies opening an investigation to identify the senders, reports Voice of America.

The anonymous messages were sent to residents in New York, Alabama, California, Ohio, Pennsylvania, South Carolina, and Tennessee. Although similar in tone, the messages varied slightly in wording.

According to the NAACP, the messages instructed recipients to report to plantations to “pick cotton.” Some also referenced the new U.S. administration. The FBI has confirmed contact with the Department of Justice, and the Federal Communications Commission (FCC) announced it is investigating the origin of these texts in coordination with law enforcement.

Tasha Danam from Lodi, California, shared that her 16-year-old daughter received a message instructing her to report to a “plantation” in North Carolina. Danam explained they’ve never lived there, and upon closer inspection, they found the location referenced was a museum.

“It’s very disturbing; we’re trying to understand what this means. I’m definitely scared and concerned,” said the mother of the 16-year-old.

At first, they thought it was a joke, but after the emotions intensified following the Tuesday presidential election, they decided to report it to the police.

“I am not a slave, my mother was not a slave, but we are only a few generations removed from that. When you think about how brutal and horrifying slavery was for our people, it’s truly concerning,” Danam added.

Nimrod Chapel, President of the NAACP branch in Missouri, stated that students, members of the organization, received messages referencing Donald Trump’s election victory and calling them to “pick cotton” the following Tuesday.

“This points to a well-organized group with resources, determined to target Americans based on skin color,” noted Chapel.