A US military helicopter has accidentally dropped a container full of ammunition on the roof of an elementary school in the southern state of Texas, leaving a gaping hole but no injuries.

The incident took place on Thursday afternoon after Parkland Elementary School in El Paso had already been released, causing a portion of the school to be without power, the Ysleta Independent School District said in a statement cited in a Fox News report.

According to the report, military police responded to the scene of the accident and an investigation is underway.

Local police, the report added, retrieved the ammunition and will return them to the military police at Fort Bliss Army base.

The military base will reevaluate its current flight patterns to ensure a similar incident doesn't happen in the future, a spokesperson stated as cited in the report.

“I'm extremely sorry for any damage done to the neighboring elementary school, and I am grateful that no one was injured,” Col. Jay Hopkins, commander of the 1st Armored Division Combat Aviation Brigade, said. “The incident is under investigation.”