"The medical center invested quite a bit of money to upgrade the facility," he said.
The pump house remained "bone dry," Cohen said. But water shoved aside plastic and plywood defenses and infiltrated the fuel vault, where sensors detected the potentially damaging liquid and shut the generators down. "The force of the surge that came in was unbelievable. It dislodged our additional protection and caused a breach of the vault as well," Cohen said.
The power at NYU went out in a flash, leaving the staff scrambling to evacuate 300 patients with no notice.
Dr. Robert Berg, an obstetrician, said that when he lost power in his apartment, he went to the hospital to charge his cellphone and was stunned to find it in chaos.
"It didn't really occur to me that the hospital was going to be in trouble," he said. Even after finding the lobby dark, "I thought, 'We'll have power upstairs. We're an operating room.'"
He wound up carrying two patients down flights of stairs on a "med sled."
"There was a Category 1 outside and a Category 4 inside," he said. "I can't say that they were very well prepared for it."
That has left only one hospital, Beth Israel Medical Center, functioning in the southern third of Manhattan. It is also on backup power, but brought in two huge new generators Thursday, just in case.
Aviles said Bellevue might be out of commission for at least two more weeks. NYU Langone's generators are operating again, but the hospital is waiting for Consolidated Edison to restore its power before it starts taking patients again. That could happen in a matter of days.
Flooding may pose less of a danger to the hospital's power supply in the future. Construction is under way on a new power plant, at a cost of more than $200 million, that will run on natural gas and supply all the hospital's power needs.
"It's a tremendous facility, with a lot of hardening built into it," Cohen said.
AP Medical Writer Mike Stobbe contributed to this report.