CHICAGO (CBS) — While taking finals, Whitney M. Young Magnet High School students were placed briefly on lockdown on Tuesday after reports of a man with a gun outside campus, but it apparently was a police training exercise that was not reported to school officials ahead of time.

Whitney Young principal Joyce Kenner, in an email to parents, called the incident “inexcusable and a disruption to our school.”

The lockdown lasted for about five minutes before school police officers were able to determine that the neighboring Police Academy was conducting a training exercise under a nearby bridge.

To make matters worse, it happened during final exam week at the school.

“When you have a high school next door, and with everything that’s been happening these past few years with shootings, it’s like, at least give us a heads up,” said Whitney Young student Christian Alvarez.

Here is the full text of the email sent by Kenner to Whitney parents:

I called a lock down at our school for approximately 5 minutes this afternoon. It was reported by 3 students that there was a man with a gun outside between two of our buildings. Our police officers went outside and it was determined the Police Academy next door was conducting a training exercise under one of our bridges. I think this is inexcusable and a disruption to our school. Our two police officers are on their way to the Academy to speak with the Commander about this incident.

In a statement, a CPD spokeswoman said:

The Chicago Police Academy was conducting training outside of the Academy. There was a call for a person with a gun. The individual who was seen was participating in the training drill. The call was cleared immediately when it was determined this was part of academy training.

There was a miscommunication between the Academy and the school. The school will be notified of all outside training in the future.