A photographer's haunting images of Pakistanis trapped in forced labor has triggered an outpouring of donations to help end the illegal practice.

The photographer, Brandon Stanton, usually chronicles everyday New Yorkers on the popular blog Humans of New York. This month, however, he visited Pakistan and posted images and the stories of the people he encountered there — including Syeda Ghulam Fatima, a campaigner against what's known as bonded labor.

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"Throughout rural Pakistan, illiterate and desperate laborers are tricked into accepting small loans in exchange for agreeing to work at brick kilns for a small period of time," Stanton wrote in one of a series of posts dedicated to the exploitation.

"But due to predatory terms, their debt balloons, growing larger as time goes on, with no possibility of repayment, until these laborers are condemned to work for the rest of their lives for no compensation," he wrote. "If the laborer dies, the debt is passed on to his or her children."

The response to the posts — each of them shared or commented upon hundreds of thousands of times — led Stanton to set up an Indiegogo campaign to raise $100,000 for Fatima's organization, the Bonded Labour Liberation Front, which estimates that 4 million Pakistanis work at the kilns in bonded forced labor.

By early Wednesday — four days after the campaign was launched — more than $2.1 million had poured in.

"Thank you to everyone who has opened their hearts and donated to our cause," Fatima said in a statement Tuesday. "I struggle to find the words, I don't think I have the words to tell you how grateful we are. ...

"Our responsibility now is to honor what you have trusted us with, and we will. We have a lot of work ahead of us, but we want to build a real freedom center in Lahore, where we can work on not just releasing families but rehabilitation," she said. "We want workers to be treated with the rights they deserve as citizens."