Law enforcement agencies in Nebraska, Nevada, South Dakota and Texas reported temporary outages to 911 services before saying hours later that services had been restored. It was not immediately clear what caused the outages or whether they were related.

Also unclear was whether any emergency situations were impacted. The National Highway Traffic Safety Administration, which houses the National 911 Program, said in a statement that its Office of Emergency Medical Services “is monitoring this issue.” A spokesperson didn’t immediately respond to a request for additional information. A message also was left Thursday with the Federal Communications Commission.

The South Dakota Department of Public Safety said in statement posted on social media Wednesday night that it was aware of a 911 service interruption throughout the state. The agency noted that texting to 911 was working in most locations and people could still reach local law enforcement through non-emergency lines. Less than two hours later, the agency said service was restored to the state’s 911 system.