(This April 22 story has been refiled to correct to show that race is held annually on the first Saturday, not Sunday, in May.)

(Reuters) - Human traffickers are likely to prey on vulnerable young women and children at this year’s Kentucky Derby, state and local officials warned on Monday, and urged spectators to be alert to people with matching tattoos or branding marks.

The Derby, the best-known horse race in the United States, takes place this year on May 4 and is expected to draw more than 150,000 people to Louisville, Kentucky. Law enforcement officials and anti-human trafficking activists told a news conference that like most major sporting events, the world-famous race would also attract predators looking for victims and buyers of sex, sometimes known as johns.

“By raising awareness with partners, our community will be better prepared to stop traffickers at this Derby,” Kentucky’s Attorney General Andy Beshear said in a written statement.

“While there is no one single indicator of trafficking, there are several signs that are common in victims including traveling together, having identical tattoos, branding and not being able to identify where they are or where they are staying,” Beshear said.

Pimps and traffickers are known to mark their victims with branding irons to show their control, trafficking experts say.

The attorney general’s office published a poster listing possible signs that someone is a human-trafficking victim, including appearing malnourished or suffering from physical injuries, avoiding eye contact, lacking official identification, sounding scripted or rehearsed in social interactions or showing signs of a loss of time and place.

“This time of year should be filled with jubilation for everyone in our community, but unfortunately the crowds drawn for these celebratory events are used to enslave and exploit the vulnerable,” Donna Pollard, founder of Louisville-based Survivors’ Corner, said in the statement.

Fans who spot someone they suspect is being trafficked were urged to call 911 or the National Human Trafficking Hotline, at 888-373-7888.

A University of Louisville study of 95 substantiated cases of child trafficking in Kentucky between 2013 and 2018 found that 87 percent of the victims were female and most were teenagers trafficked by a family member.

Last year, the attorney general’s office was involved in more than 30 arrests or citations involving human trafficking, Beshear said.

The 2019 Kentucky Derby is expected to have the biggest purse in the history of the race, which was inaugurated in 1875 and is held annually on the first Saturday in May at the Churchill Downs racetrack in Louisville.

The race is the first leg of the so-called Triple Crown, which also features the Preakness Stakes and Belmont Stakes.