UPDATED @ 4 p.m.: A power outage caused the elevator problem that trapped a Penn State student early Sunday, the university has reported. New details are incorporated into the story below.

A Penn State graduate student was stuck inside a stalled elevator for nearly seven hours early Sunday, University Park police said Monday.

The student boarded an elevator in Keller Building about 2:30 a.m., said Tyrone Parham, deputy police director.

Within moments, an unexpected power failure cut off electricity to the elevator, spokeswoman Lisa Powers said. She said the graduate student, whose name was not released Monday, had left his cell phone at his desk.

"There is nothing mechanically wrong with the elevator, and it did not need to be repaired," Powers wrote in an e-mail message. "After a power outage, it just needs to be reset. It tends to 'forget' what it was doing (going up or down) during a power outage."

Parham said the affected elevator car is not equipped with an emergency phone, so the trapped student was left to communicate through more primitive means.

At 7:43 a.m. Sunday, someone else inside Keller Building called campus police to report that he thought he heard a person trapped in an elevator.

But the caller immediately called police again to say that he had been mistaken, so officers called off a response, Parham said.

At 8:25 a.m., the caller telephoned campus police once more, this time to say that he had checked a second elevator in the building and found that there was definitely someone caught inside, Parham said. He said the caller is either another graduate student or a university employee.

"We were running back up there" at that point, Parham said.

Once they got the observer's third call, he said, police quickly arrived on the scene and summoned help from the Office of Physical Plant. A technician released the student from the elevator car at 9:20 a.m., according to police.

Parham said the student had been working in the building. There's no indication that the incident was alcohol-related, and the student did not suffer any medical problems, he said.

Keller Building was built in 1963. Powers said Penn State is already in the process of retrofitting all its elevators with emergency phones -- including the 315 elevators on the University Park campus.

So far, she said, about 150 elevators on the campus have been retrofitted with the phones. The upgrades cost $15,000 to $20,000 apiece, Powers said.