A Pennsylvania school district is investigating complaints that students on a class trip to the U.S. Holocaust Memorial Museum posted pictures making light of some exhibits.

Superintendent Ed Bowser of the Forest Hills School District said Friday officials are looking into social media posts from the senior class trip Wednesday to the Washington, D.C., museum.

Senior class president Gage Singer tells The Associated Press that most students were respectful, but a small number "made a mockery of what they saw," including in a Snapchat post of shoes confiscated from concentration camp prisoners.

In a letter posted online, Singer called the conduct "unacceptable," and apologized on behalf of the entire class.

Bowser says any student discipline will be handled privately.

Forest Hills is about 80 miles (129 kilometers) east of Pittsburgh.