The Global Positioning System used to track sex offenders in the United States shut down for several hours this week.
The malfunction left authorities in 49 states blind to the movements of more than 16,000 offenders for 11 hours on Tuesday.
BI Incorporated, the company that manufacturers the tracking system, says it unexpectedly hit its data storage capacity on Tuesday.
"Due to a system failure beyond our control, we faced a challenging and unprecedented event for our electronic monitoring center," Wisconsin Department of Correction Secretary Rick Raemisch said in a statement.
But thanks to the agency's emergency plan and the cooperation from local law enforcement, "the situation was managed safely and efficiently with the number one priority being public safety," he said.
Roughly 900 government agencies across the U.S. contract with BI on monitoring and notification services, including real-time monitoring and delayed notifications on the location of sex offenders.