A hotel guest who repeatedly refuses housekeeping services. A room paid for in cash, or a guest who doesn't bring luggage. An older man checking in with a younger girl who looks disheveled or frightened.

All of these are of possible tip-offs to juvenile sex trafficking and part of a training session Tuesday at a downtown Minneapolis hotel. Hennepin County and the city launched the education effort with the Minnesota Lodging Association to train hotel employees to spot potential underage sex trafficking.

"It's as easy to dial up for a juvenile to come to your hotel room as it is to order a pizza," Minneapolis police Sgt. Greg Reinhardt said. With the help of ads online at the notorious backpage.com, young girls and boys can be served up to be raped within a half-hour, he and others said.

The training was the first of its kind in Minneapolis. Ramsey County Attorney John Choi had held a similar event in Roseville after a hotel employee there led police to a sex peddler who ended up with a 21-year prison sentence.

"Hotel employees are experts at what happens in hotels," said Minneapolis police Sgt. Grant Snyder, who was one of the trainers at the afternoon session.

Hotel workers know human behavior and often can sense when something is wrong, he said. The training also is about tearing down barriers between law enforcement and hotel employees, many of whom are new to the country and might not trust police.

Dan McElroy, president of the trade group Hospitality Minnesota, said hotel workers are told, "If you see something, say something." The hotel management then can contact investigators. "We have to build their confidence," he said of the workers.

Everyone agreed the problem is widespread.

Juveniles who are caught up in sex trafficking come from all socioeconomic backgrounds and races, numerous law enforcement leaders said at a news conference before the training session. Minneapolis Police Chief Janeé Harteau said the city has encountered victims from Lake County and from Milwaukee.

Reinhardt said Minneapolis made 19 arrests last year in juvenile sex trafficking.

The children who are trafficked now can get help under a Safe Harbor law that allows them to be treated as victims and get social services rather than be treated as juvenile offenders.

City Council Member Elizabeth Glidden had a message for sex traffickers, "We are here to stop you."

The city, county and hospitality officials said they expect to conduct many more training sessions as part of a push to focus on juvenile sex trafficking.

Other indicators of trouble: men visiting for short amounts of time, people waiting in the lobby, money exchanging hands in the hallway or parking lot, notes with women's names, numerous laptops and excessive pornography or sex paraphernalia.

And, finally, a handout to the workers read: "Call 911. No concern is too small."

Rochelle Olson • 612-673-1747 Twitter: @rochelleolson