NEW YORK (Reuters) - A tornado damaged the building housing a nuclear research reactor at Kansas State University, the university told the U.S. Nuclear Regulatory Commission in an event report early Thursday.

The tornado caused extensive damage to the building, but no damage to the reactor, which had been shut down properly earlier in the day, the university said.

The reactor is located in Manhattan in Riley County, about 120 miles west of Kansas City, Missouri.

Because of the event, the university declared an alert, which is the second lowest of the NRC’s four emergency classifications.

There are more than 30 operating research and test reactors in the United States, according to the NRC’s website.