A software malfunction caused a significant outage in New York City's 911 system Tuesday, blocking nearly 1,700 emergency calls for approximately seven hours and potentially impacting up to 400 residents.

The issue affected the Public Safety Answering Center II in the Bronx, one of two centers serving the city's five boroughs. The outage began at 3:13 a.m. and was resolved by 10:19 a.m. The NYPD confirmed the number of calls that did not reach operators, as well as the estimated number of individuals affected. The city's other call center, located in Brooklyn, remained operational.

During the seven-hour period, a total of 5,659 calls for emergency services, including the Fire Department, Emergency Medical Services, and NYPD response, were received by the system. Officials stated that operators were unable to hear callers during the disruption. The city has since conducted extensive overnight testing and is closely monitoring the system's performance.

City Hall spokesman Jeremy Edwards indicated that the problem is believed to be a software failure, not a cyber attack. An investigation into the precise cause of the glitch is ongoing, with officials focused on understanding the circumstances, ensuring affected callers receive follow-up, and implementing measures to prevent future occurrences.

The city's 911 system underwent a significant overhaul beginning in 2004 under then-Mayor Michael Bloomberg. However, this project was marked by delays, cost overruns, and mismanagement, with a 2015 report estimating the total cost exceeded $2 billion.