The American Civil Liberties Union on Tuesday outed Facebook, Twitter, and Instagram for feeding a Chicago-based company their user streams—a feed that was then sold to police agencies for surveillance purposes.

After the disclosure, the social media companies said they stopped their data firehouse to Chicago-based Geofeedia. In a blog post, the ACLU said it uncovered the data feeds as part of a public records request campaign of California law enforcement agencies. Geofeedia touts how it helped police track unrest during protests.

In one document, Geofeedia hailed its service because it paid for Twitter's "firehose" and because it is the "only social media monitoring tool to have a partnership with Instagram."

"Geofeed Streamer is unique to Geofeedia and has numerous uses (Ie: Live Events, Protests—which we covered Ferguson/Mike Brown nationally with great success, Disaster Relief, Etc)," said one document (PDF) that Geofeedia sent to a police agency, which was then forwarded to the ACLU.

Following the ACLU post, Twitter tweeted, "Based on information in the @ACLU's report, we are immediately suspending @Geofeedia's commercial access to Twitter data."

Nicole Ozer, an ACLU civil liberties director in California, said, "The ACLU shouldn't have to tell Facebook or Twitter what their own developers are doing. The companies need to enact strong public policies and robust auditing procedures to ensure their platforms aren't being used for discriminatory surveillance."

The ACLU said that "after we reported our findings to the companies, Instagram cut off Geofeedia's access to public user posts, and Facebook has cut its access to a topic-based feed of public user posts."

Geofeedia, which did not respond for comment, says it has more than 500 customers, including the Denver Police Department. That agency recently signed a $30,000 annual deal with the company. The money came from the agency's "confiscation" fund. The department's intelligence agency's top brass wrote that it would allow cops to analyze and respond in real time to "social media content from anywhere in the world."

"You are able to see real-time potential threats being made to an event," Denver Police Lt. William Mitchell said. He added that the data feeds helped with the Boston Marathon bombing investigation and aided police in finding a woman who made online threats during the Super Bowl. "It has the ability to identify criminal suspects and their actions as they post them to social media," he said.

Los Angeles authorities had written in a grant application that as many as 500 police departments nationwide were using Geofeedia.

Listing image by Geofeedia