BRIDGEWATER, Mass. — A Massachusetts school district has apologized after a photo appeared to show two white children holding leashes attached to a black child.

The children were wearing 17th century clothing in the photo that was taken in a third-grade classroom at an elementary school in Bridgewater. The two white children were standing while the tethered girl was kneeling on the floor. Their teacher was also shown in the photo, which has circulated on Facebook and generated complaints of racial insensitivity.

Bridgewater-Raynham Regional School District Superintendent Derek Swenson explained in a statement Thursday that the children were learning about Colonial-era clothing and a portion of the lesson dealt with tethering straps that were commonly used to help toddlers learning to walk.

Swenson says the school district understands why the photo could be perceived differently.