In a matter of days, more than $2 million has been raised for the Bonded Labour Liberation Front, a group that's working to end bonded labor in Pakistan. It all started with a single photograph, according to CNN. The photo of Syeda Ghulam Fatima, founder of the Bonded Labour Liberation Front, was posted to the "Humans of New York" Facebook page. "Humans of New York" was started by Brandon Stanton, a photographer who wanted to show the day-to-day lives of New Yorkers.

"Fatima has devoted her life to ending bonded labor. She has been shot, electrocuted, and beaten numerous times for her activism," Stanton said on the Facebook page. He also posted photos of workers in Pakistan laboring in the brick kilns.

A donation link was added to the photos. In just 12 hours, $1 million in donations came in through the link. After 72 hours, that amount had doubled.

Very poor brick kiln workers labor long hours to chip away at debts. If they die before the debt is paid, it passes to the next generation, according to Business Insider.

"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 said in the post, according to NBC News. The Bonded Labour Liberation Front estimates that 4 million Pakistanis work in kilns as bonded laborers.