It started out like any other Uber transaction.

Keith Avila, a photographer who also drives for the ridesharing company, picked up two women and a girl at a home in Sacramento, California on Monday. As they got into the car, Avila noticed the girl looked young.

“She looked like she was about 12,” he tells PEOPLE, “but she was wearing a short skirt that showed off her legs.”

Almost immediately, Avila says, the conversation began to raise red flags. “The lady in the back started getting really upset,” he recalls. “She was yelling at the girl, ‘You need to get your priorities straight. We need to make this money.’ ”

As he drove, Avila says he tried to process what was happening. “I was thinking, ‘What does she mean by money? Is she selling drugs?’ ”

He says the situation soon became more clear: “The woman in the back started coaching the girl. She said, ‘before you go in, check for weapons. When you hug them and touch them, pat them down.'”

The conversation turned to talk about payment. “The woman told the girl to get the donation first,” Avila tells PEOPLE. “She said, ‘Ask if they have your donation before you go into the room.’ ”

Avila, a 34-year-old married dad, then believed that the woman was a pimp and that the girl was a victim of sex trafficking. And he was driving them to a hotel.

“I was 100 percent sure I knew what was happening,” Avila tells PEOPLE. “It wasn’t 99.999 percent. It was 100 percent. And I knew I had to do something, but I didn’t know exactly how I was going to do it. I wondered if I should take pictures with my phone.”

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As they drove up to the hotel, one of the women got out of the car with the girl, Avila says. The other woman stayed in the car and made one more phone call.

“It was very professional,” he says. “She sounded like a dentist’s secretary. She said, ‘I just want to make sure there’s no law enforcement there.’ And then she said, ‘Room 110.’ ”

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As soon as the second woman got out of the car, Avila drove a few hundred feet down the road and called the police, who arrived within minutes. With Avila’s descriptions, they went straight to Room 110.

As it turns out, Avila’s hunch about may have been right. Police say that the girl was a 16-year-old prostitute and the two women with her were allegedly involved in sex trafficking. (A police spokesperson confirms Avila’s account of his involvement to PEOPLE.)

Authorities have arrested Destiny Pettway, 25, and Maria Westley, 31, and charged them both with pimping and threatening a minor. They are being held without bond. It’s unclear whether they have retained attorneys or entered pleas.

Police also arrested the suspected john, 20-year-old Disney Vang. He was arrested and charged with soliciting a prostitute and sexual contact with a minor.

He did not return PEOPLE’s call for comment, and it’s unclear if he has retained an attorney or entered a plea.

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Police say that they’re grateful to Avila for getting involved.

“He could’ve said nothing. Went on his way, collected his fare. And then that 16-year-old victim could’ve been victimized again by who knows how many different people over the next couple of days, weeks, months,” Elk Grove police Officer Chris Trim told FOX 40.

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Uber is also heralding Avila’s actions. “What Keith did is incredible,” a company spokeswoman told The Washington Post in a statement. “We appreciate his quick response and professionalism in a difficult situation.”

Avila tells PEOPLE that he’d do the same thing over again.

“I knew what was happening,” he says, “and I would never have been able to ignore it. It was the right thing to do.”