Updated

More than two dozen students have spent the night in a hospital after carbon monoxide leaked at their Nashville private school.

Drexel Preparatory Academy principal Cheryl Bowman told WTVF-TV (http://bit.ly/ULQFal ) students began coming to the office Monday morning complaining of flu-like symptoms. Officials decided to cancel classes.

After students were sent home, the school got a call from Vanderbilt University Children's Hospital, saying several students had been brought in and showed high levels of carbon monoxide.

Workers found a hole in a heating unit that serves the central part of the school, where the kindergarten and first-grade classes are located.

Twenty-eight students were admitted to the hospital and put on oxygen overnight. Carbon monoxide is a colorless, odorless gas produced by combustion.