AT&T, T-Mobile and Sprint have sold access to subscribers’ real-time location data to aggregators, which in turn have sold it to about 250 bounty hunters and related businesses, Motherboard reported Wednesday.

In some cases, the data allowed users to track individuals to their specific locations inside a building.

Some companies made thousands of location requests to data brokers; one company made more than 18,000 such requests in just over a year.

The news, which sparked widespread outrage, prompted a range of responses, including the following:

1. A letter from 15 United States senators to the U.S. Federal Trade Commission (FTC) and U.S. Federal Communications Commission (FCC) demanding action;
2. A tweet from FCC Commissioner Jessica Rosenworcel saying that the agency needs to investigate the issue; and
3. Promises from the carriers that they either have ceased the practice or planned to do so shortly.