911 lines crash in Las Vegas, South Dakota, parts of Nebraska and Texas

Lumen, the company that provides the call systems, explained that the outages in Nevada, South Dakota, and Nebraska were caused by the installation of a light pole by a third party. There has been no explanation provided for the outages in Texas.

"Some customers in Nevada, South Dakota, and Nebraska experienced an outage due to a third-party company installing a light pole," Lumen said in a statement to ABC News, noting that it was "unrelated to our services."

"Our techs identified the issue and worked hard to fix it as quickly as possible," the company added. "We restored all services in approximately two and a half hours. We apologize for the inconvenience and appreciate our customers' patience and understanding."

Lumen is the sole provider of emergency call services in South Dakota, and as such, the state's entire system was down for the duration of the outage.

The South Dakota Department of Public Safety explained that the State 911 Coordinator was "in constant contact" with Lumen and the twenty-eight 911 dispatch centers across the state.

"Although some calls may not have gone through, the system allows dispatch centers to identify the phone number of callers and return those calls," the SDDPS added.

During a press conference on Thursday, Sioux Falls Division Fire Chief Mike Gramlick called the outage "unprecedented in terms of its duration and magnitude."

The largest metropolitan area to be impacted was Clark County, in Nevada. When service returned to normal, the Las Vegas Metropolitan Police Department said that "all of the individuals who called during the outages have been called back and provided assistance."

The Federal Communications Commission has launched an investigation into the matter.