It happened at the Alvin E. Gershen Apartments on the 1600 block of Klockner Road Hamilton Township.
Officials say the unplanned outage occurred during an equipment test at the tower.
"These apartments get over 90, 100 when there's no AC blowing. That's dangerous," said resident Ken Snyder.
Residents told Action News they were being voluntarily evacuated one-by-one by firefighters through an elevator that was being powered by a generator.
A majority of residents chose to wait it out in the lobby, while others sheltered in the building next door, or opted to stay in their apartments.
Resident Edwin Reed was worried sick about his friend who has mobility issues.
"He can't walk down the steps so it's getting hot up there, his food is gonna be going bad pretty soon," he said.
Luckily, Reed told first responders where his friend Andy Betronella was and he was taken safely downstairs.
"He is a good friend, thank you my friend," said Betronella. "I went out in the hallway and the firemen were at the elevator when it opened on the ninth floor, so that's how got down."
Hamilton Township officials say two people were taken to area hospitals for shortness of breath.
PSE&G says it was able to restore power around 2 p.m. and residents who self-evacuated were able to return to their units.
Action News has reached out to the complex's management company for comment, but we have not heard back.