New York Gov. Hochul says MTA 'uncovered a sequence of failures' that led to a 5-hour disruption and passenger evacuations on NYC subway

• New York Gov. Kathy Hochul pledged to investigate an "unprecedented" disruption to the NYC subway.
• After a brief power outage Sunday night, the signal and communications systems went offline.
• Five trains were stranded in tunnels between stations, prompting passengers to evacuate.

New York's new Gov. Kathy Hochul pledged to fix the New York City subway system after a brief power outage led to an "unprecedented" shutdown Sunday evening into early Monday.

"We need to know why the system broke down and why," Hochul said at a press conference outside the MTA headquarters in Manhattan on Monday morning.

Following her call for a review, Hochul said in a statement Monday afternoon that the MTA "uncovered a sequence of failures that resulted in some backup systems not providing power as designed last night, including an additional failure to quickly diagnose the underlying cause."

Hochul said she directed the MTA to bring on two independent engineering firms to further investigate the system failure.

Earlier Monday, Hochul said a brief power outage at around 8:30 p.m. on Sunday momentarily shuttered power to the subway system. As Gothamist reported, other people in the city noted a brief ConEdison power outage at about the same time.

"It was a momentary outage that did go to the backup system," Hochul said during a press conference Monday, The New York Post first reported. "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."

The Metropolitan Transit Agency and the New York City Fire Department evacuated hundreds of passengers on the system from the tunnels, Gothamist reported. Aside from those proper evacuations, passengers on two other trains left on their own.

The issue affected eight of the city's subway lines: 1, 2, 3, 4, 5, 6, 7, and L. Regular subway service was restored at about 1:30 a.m. on Monday, after FDNY crews searched the tunnels for any remaining passengers who self-evacuated.

"We never, ever want riders to do that," Hochul said. "It is dangerous and it caused a delay in restoration of power."

"Let me be very clear, last night was unacceptable," the governor added, according to Gothamist. "If you're one of those riders, the system failed you."

Hochul, a Democrat, took office on August 24 after former Gov. Andrew Cuomo resigned in the wake of a report from the state attorney general's office that found he sexually harassed 11 women. As the governor, Hochul is tasked with overseeing the MTA, which runs the New York City subway system.