Workers installing a light pole in Missouri cut into a fiber line, knocking out 911 service for emergency agencies in Nebraska, Nevada and South Dakota, an official with the company that operates the fiber line said Thursday.

Problems with 911 calls in a Texas city along the U.S. border with Mexico were unrelated, officials said, but the widespread outage created concerns about what was causing the problems.

For most agencies, it turned out to be the result of simple human error.

In Kansas City, Missouri, workers installing a light pole for another company Wednesday cut into a Lumen Technologies fiber line, Lumen global issues director Mark Molzen said in an email to The Associated Press. Service was restored within 2 1/2 hours, he said. There were no reports of 911 outages in Kansas City.

Meanwhile, the difficulties some cellphone callers experienced making 911 calls in in Del Rio, Texas, were apparently because of an outage involving a cellular carrier, not the city's 911 system, city spokesman Peter Ojeda said. Lumen is not a 911 service provider for Texas.

The outages prompted an investigation from the Federal Communications Commission, it said in a statement. 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.”

The outages created confusion for some people trying to reach emergency agencies.

The Dundy County Sheriff’s Office in Nebraska warned in a social media post Wednesday night that 911 callers would receive a busy signal and urged people to instead call the administrative phone line. About three hours later, officials said mobile and landline 911 services had been restored.

In Douglas County, Nebraska, home to Omaha and more than a quarter of the state’s residents, 911 Director Kathy Allen said Lumen informed the agency at 1:42 a.m. Thursday that service was restored, but the county “did experience a few more issues.” Service was fully restored by 4 a.m., Allen said in a statement.

Cut fiber lines and other problems have caused 911 outages in recent years in Nebraska. The issue was worrisome enough that the Nebraska Public Service Commission hosted a hearing on the topic in December.

The South Dakota Department of Public Safety said in statement posted on social media Wednesday night that the 911 service interruption occurred 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.

Officials in Sioux Falls, South Dakota, said during a news conference Thursday that the outage was unprecedented.

“To our knowledge, we have never experienced an outage of this magnitude or duration,” Assistant Fire Chief Mike Gramlick said.

Las Vegas Metropolitan Police Department 911 Communications warned Wednesday evening of an outage affecting 911 and non-emergency calls in a social media post. Calls from landlines were not working, but officials said they could see the numbers of those who called from cellphones.

“Dial on a mobile device, and we will be able to see your number and will call you back right away,” the department posted.

About two hours later, the department posted that service was restored, and everyone who called during the outage had been called back and provided assistance.

In Del Rio, a city of 35,000 residents, police on Wednesday posted that “an outage with a major cellular carrier” was to blame. Del Rio had the opposite problem of Las Vegas — 911 calls from cellphones didn’t work, so those needing help were urged to use a landline or another cell carrier.

The outages, ironically, occurred in the midst of National Public Safety Telecommunicators Week.