The young women worked together part-time at the Good Samaritan nursing home in Albert Lea, Minn., the Minneapolis Star Tribune reported Tuesday.

Brianna Broitzman, 19, and Ashton Larson, 18, were charged Monday with misdemeanor assault, abuse of a vulnerable adult by a caregiver and disorderly conduct, the Star Tribune reported, noting the six other defendants were identified in court only by their initials and birthdays.

The abuse allegedly occurred between January and May of this year against 15 residents with dementia, said Freeborn County Attorney Craig Nelson.

Several of the teenagers have challenged prosecutors' findings in the case, while Broitzman, Larson and their lawyers could not be reached for comment Monday, the Star-Tribune reported.