BOSTON — The 911 system across Massachusetts was restored Tuesday after going down for several hours.

The Massachusetts State Police announced at around 3:45 p.m. that the system had been restored and that people could resume calling emergency services. They didn’t provide any details behind the cause of the outage.

It was unclear how many communities were affected by the outage, said Elaine Driscoll, director of communications and policy at the state’s Executive Office of Public Safety and Security. It first was reported by several law enforcement agencies after 1 p.m.

At the time of the outage, Boston Police Commissioner Michael Cox advised the public to contact local police departments if they need help.

“In addition, if you’re having any issues that are medical related, or EMS or fire-related, you can go and pull your local call box — that’s the red light boxes that fire departments have on local street corners — to also get medical attention that way,” he said.

Boston Mayor Michelle Wu said residents shouldn’t worry about calling the correct number or facility for their emergency, but to just reach out to their nearest authorities.

“If you are experiencing an emergency, if you find your way to police, fire or EMS, we will make sure that you get to the right place,” she said.

The Massachusetts disruption caused confusion in other northeastern states, where some residents also got notifications on their phones. But authorities in Maine, New Hampshire, Rhode Island and New York all said their systems were operational.

“We are aware that some individuals in Vermont have received wireless notifications about the Massachusetts event,” said Barbara Neal, executive director of the Vermont Enhanced 911 Board. “The official reason for that is unknown but it may be related to individuals having signed up for an alerting system in Massachusetts or having been at or near the Massachusetts border when the wireless alert was issued by Massachusetts.”

Several years ago, Massachusetts suffered sporadic 911 outages. At the time, it was blamed on outages from Louisiana-based CenturyLink, which affected some Verizon customers.