NEW YORK (CBSNewYork) Gov. Kathy Hochul said Monday the New York City subway system failed riders when an “unprecedented” power surge shut down half the system and forced hundreds to evacuate through dark tunnels.

The dominoes started to fall around 8:25 p.m. Sunday when Con Edison experienced a citywide voltage dip that interrupted power to subway signals and communications.

READ MORE: Jury Begins Deliberations In R. Kelly Trial After 6 Weeks Of Testimony

“The confluence of circumstances, this perfect storm that was created, hasn’t happened before,” Hochul said.

A battery-powered back-up system engaged to keep the system running. The system is designed to return to Con Ed power when it becomes available, but that did not occur.

“But when it tried to go back to normal, there was a surge, an unprecedented surge, that resulted in the subway losing signalization and communication ability,” said Hochul.

WATCH: Gov. Hochul Gives Update On Subway Outage  

An alert system that should’ve notified the MTA of the failures did not provide alerts. Supervisors were unaware the system was still running on batteries for about 45 minutes. The batteries ran out at 9:14 p.m., causing major service interruptions.

The outage impacted about half the system. Hochul said 83 trains on the 1-7 lines and the L came to a temporary halt. There was no communication ability between the command center and the trains.

Five trains were stuck between stations. Two were evacuated by MTA personnel.

“They made us exit the rear of the train,” one rider told CBS2.

“We came out and we were walking on the side of the tracks,” said another rider. “And it was dark. There was nobody there with flashlights or nothing. I had to use my phone to light up the way for my wife and me.”

“It’s like a horror film, walking in the tunnels, in the dark,” Crown Heights resident Assaph Shimon told CBS2’s Nick Caloway.

Two more trains had riders that did self-evacuations. They got out and walked through the tunnels on their own.

READ MORE: NYC Teacher, Principal Unions Warn Of School Staffing Shortages When Vaccine Mandate Takes Effect; De Blasio Says Substitutes Standing By

Acting MTA Chair Janno Lieber said that was very dangerous.

“We really discourage that,” said Lieber. “Not just because it’s super unsafe with an active third rail, but also because it delays. When that happens, we have to shut down the third rail power, and it takes much longer for the whole system to get reactivated. That’s what happened last night.”

Rescue crews inspected the tracks around those trains to make sure they were clear before restoring service at around 1:30 a.m. Monday.

“Let me be very clear, last night was unacceptable,” Hochul said. “If you’re one of those riders or people relying on safe transport, the system failed you.”

The governor ordered a review of the incident. An external review will be conducted by two independent engineering firms to make recommendations to ensure something like this doesn’t happen again.

“Transit workers did a great job during the emergency, demonstrating once again why you need a fully staffed system, and that includes having both a conductor and a train operator on the train,” Transport Workers Union Local 100 said in a statement. “Conductors walked through the cars of stalled trains, urging riders to remain calm, and providing them the latest information they had.”

Officials said subways were running normally Monday without residual impacts.

MORE NEWS: Mayor De Blasio Says He Will Visit Rikers Island Next Week Amid Growing Pressure

CBS2’s Nick Caloway contributed to this report.

CBSNewYork Team