NEW YORK — A power outage shut down service on the 1, 2, 3, 4, 5, 6, 7 and L subway lines Sunday night, stranding hundreds of customers between stations.

The MTA said Monday afternoon that their system switched to short-term battery power when Con Edison was impacted at around 8:25 p.m. Sunday, but did not switch back to Con Edison's system when power became available. As a result, the major disruption occurred when the batteries ran out at around 9:15 p.m.

According to the MTA, an alert system did not notify subway management about the failures, which left officials unaware that batteries were still powering the system. 

The MTA did say that they have two backup generators for situations like these, but it is unclear why they were not activated.

The outage affected more than 80 trains overnight. About 550 riders were evacuated from the system, with roughly 100 of them doing it on their own, the MTA said. 

"We experienced what is known as self-evacuation, where riders decided to leave on their own,” Gov. Kathy Hochul said. “We never ever want riders to do that, it is dangerous and it caused a delay in restoration of power."

The governor said she's calling for an investigation into what caused the disruption. 

"Last night was unacceptable. If you're one of those riders or people relying on safe transport, the system failed you,” Hochul said. “The MTA is the lifeblood of this city and a disruption of this magnitude can be catastrophic."

She also pointed out how much worse the incident could have been if it had occurred during busier hours.

"A disruption of this magnitude can be catastrophic and thank God if you think about the time that this happened, it was a time of low ridership, it was on a weekend night, late at night, and I can only imagine how devastating this would've been for thousands of New Yorkers had this occurred during a morning commute like this morning,” Hochul said.

In her statement later in the day, Hochul said she has directed the MTA "to retain two independent engineering firms to assist in a thorough deep dive of what happened and make recommendations to ensure this does not occur again."

In a news conference held hours after the governor’s, Mayor Bill de Blasio said he’s working with the state and MTA leadership to determine what happened because “it is not clear yet—a full investigation is going on.”

He also said that though many subway riders were inconvenienced, there were no injuries caused by the subway disruptions.

The situation is contained and full subway service is coming back, he said.

“The good news is that we had a temporary situation, but we need to know more about it,” said de Blasio. “We need to understand how this could happen and how to make sure it does not happen again.”

Hochul said that while the cause is still under investigation, there's no indication of any malicious action.