NEW YORK (AP) — Columbia University says it's strengthening its procedures after it accidentally sent acceptance notices to 277 prospective students and then recalled them.

The New York Times (http://nyti.ms/2leKX5Q ) says the erroneous emails were sent Wednesday. About an hour later, a retraction and apology were sent out.

The second email attributed the incident to human error and said the school was working to ensure it wouldn't happen again.

It said Columbia values applicants' "energy and enthusiasm" and regrets the "stress and confusion" the mistake caused.

Columbia did not immediately respond to a request for request Friday.

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Information from: The New York Times, http://www.nytimes.com