Officials at the U.S. Naval Academy have started an investigation into alleged drug use among midshipmen, a probe that also involves the Naval Criminal Investigative Service, according to an academy spokesman.

Cmdr. David McKinney, Naval Academy public affairs officer, said in an emailed statement the investigation recently began after “receiving a midshipman report of alleged recreational drug use.”

“The investigation has been ongoing over the past two and a half months and the results of the investigation are still pending,” he said. “We are continuing to work with [the Naval Criminal Investigative Service] on these reported allegations. The Navy has a zero tolerance for drug abuse and takes all allegations of misconduct very seriously.”

It is not clear how many midshipmen are under investigation, nor is it clear what drugs they are accused of using.

There are about 4,400 students at the Naval Academy in Annapolis.

Ed Buice, public affairs officer for the Naval Criminal Investigative Service, said in an email that agency does not discuss details of ongoing investigations.

In 2011, several midshipmen were removed from campus for possessing or using a synthetic form of marijuana, which an investigation showed was widely used at the Naval Academy.