What to Know Employees learn classic signs of human trafficking, like guests paying in cash one day at a time and various men being escorted to a room.

They also learn about disturbing real-life situations that happened on Marriott properties where trained employees saved people.

Hyatt and Hilton are the only other major hotel chains that require training for all employees.

Marriott International is in the middle of a huge effort to make sure all employees at each of its properties are trained to recognize human trafficking.

Brijae Sledge, a bartender at the Renaissance in downtown D.C. recently completed the training.

"I definitely keep a close ear and a close eye on things that are going on," she said.

She's one of almost a half-million Marriott employees who have completed mandatory training.

Employees learn the classic signs of human trafficking, like guests paying in cash one day at a time and various men being escorted to a room. They also learn about disturbing real-life situations that happened on Marriott properties where trained employees saved people.

The message is clear: They have to be vigilant and involved.

“As a hotel company, Marriott International is taking a proactive approach on this,” Director of Social Impact and Global Responsibility Tu Rinsche said. “We're not ignoring the issue; we're not denying it. We accept that, and unfortunately it happens in hotels.”

And it's happening at record rates, according to Ending Child Prostitution and Trafficking (ECPAT), a global network working to end the exploitation of children.

“This training is extremely urgent,” said Michelle Guelbart, of ECPAT. “This is the most important industry to train on this issue, period.”

But according to ECPAT, only three major hotel chains worldwide — Marriott, Hyatt and Hilton — make the training mandatory for all employees.

ECPAT is building a database where guests can see whether the hotel they book makes the grade.

“You'll be able to see in the first year what companies have policies, how many are training, who's training, what is that training, what does it look like,” Guelbart said.

Reported by Susan Hogan, produced by Meredith Royster and edited by Perkins Broussard.