Stony Brook University officials said electric power had been restored to most of its campus Friday following an overnight blackout.

The school lost power about 12:15 a.m., but it was restored to most areas, except the administration building, within one hour, spokeswoman Lauren Sheprow said.

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She said Stony Brook University Hospital had to operate on backup power for about an hour, and that several people trapped on elevators “were quickly removed and were not in distress.”

A spokesman for PSEG Long Island said it supplied power to the university, but that the outage occurred in a substation operated by the school.

Sheprow said, “The suspected cause was a steam leak in the administration building, which caused an electrical interruption.”

The administration building was closed for the day due to the outage, the university said in an advisory on its website.

“Limited student services” were made available in the on-campus Melville Library, according to the advisory.