Madison, NJ – Five students were sent to the hospital early Wednesday morning after a carbon monoxide alarm alerted officials to the presence of the odorless gas in a dormitory, according to a spokesman for the university.

Drew University Class of 2016 arrivalFoster Hall at Drew University was evacuated early Wednesday morning after an alarm indicated the presence of carbon monoxide, according to a university spokesman. Pictured in this file photo, Ehinger Center at Drew University.Justin Zaremba/NJ.com

At about 2 a.m., Drew Public Safety officers responded to a carbon monoxide alarm in Foster Hall, which is also known as the Suites Complex, Drew University spokesman David Muha said in an email.

After the building was evacuated, the Madison Fire Department and officials from Public Service Electric & Gas were called to respond to the dorm, Muha said.

Muha said PSE&G determined the source of the alarm was a hot water heater on the first floor, which was then turned turned off.

“The building was vented and students were cleared to return to their rooms at approximately 3:45 a.m. after readings taken by both PSE&G and the Madison Fire Department determined that the air was safe,” Muha said.

Five students reported feeling unwell during the evacuation and were transported to Morristown Medical Center for evaluation as a precaution, Muha said. All of the students were treated and released, he said.