The outage lasted less than half an hour Sunday morning.
The Orleans Parish Communication District described the 30-minute outage as "technical difficulties" in a Sunday Facebook post and then gave an update saying systems had been restored, as nola.com first reported.
"New Orleans 9-1-1 experienced a brief outage this morning," Orleans Parish Communication District Executive Director Tyrell Morris said during a Sunday press conference. "Our technology department worked with local and state vendors and service was quickly restored."
The communications district's initial assessment was that the outage was linked to an issue with the city's AT&T network, a spokesperson told FOX Business, but the office is "currently conducting an investigation into the matter so cannot confirm" the cause of the outage "until the investigation is complete."
The city is asking residents to make 911 calls for "life-threatening emergencies only," including street flooding, power lines that have gone down and people or cars trapped in floodwater.
"Remember, 9-1-1 is for life-threatening emergencies only. Emergency response will be extremely limited during this weather event. Please shelter in place until we have informed you that it's safe to go outside," Morris said during the press conference.
More than 100,000 New Orleans residences were without power in southeast Louisiana as of Sunday afternoon, according to data from Southern energy company Entergy, LLC.
"Crews from at least 22 states and D.C. are joining the restoration process for #HurricaneIda," Entergy tweeted Sunday.
Hurricane Ida grew into a Category 4 storm by Sunday morning with maximum sustained winds of 150 mph. The storm made landfall around noon, and the National Hurricane Center is warning of "catastrophic" wind damage the southern part of the state.
Authorities are asking residents to evacuate immediately or shelter in place.