Verizon is chalking up last night’s 2½-hour outage of 911 calls in Baltimore to equipment that mistakenly directed the emergency calls to an empty back-up call center.

The outage started at 7:47 p.m. and lasted to about 10:15 p.m.

During that period, callers to 911 heard a recorded message telling them that “all operators are busy. Your call will be answered in turn. . .”

Police Commissioner Kevin Davis said the city literally ducked the bullet.

There were no fatal or non-fatal shootings reported during the system’s breakdown, he said at a City Hall press conference today. It is unclear whether fire or emergency medical calls went unheeded during the outage.

Once they realized that 911 calls were failing around 8:20 p.m., fire and police personnel gathered at police headquarters and used social media to advise residents to call 311 to report emergencies. The local media also spread the message.

Verizon spokesman John O’Malley said this afternoon that the company is reviewing why the calls were misdirected.

The company is paid $260,000 a year to maintain 911 equipment for the city.

As many as 4,000 911 calls are received by the system every day. City officials said they could not say how many 911 calls were made during the service interruption or whether emergency response times were delayed.