A passerby noticed the two children, ages 2 and 3, inside a car in the Walmart parking lot and quickly notified police, according to WCVB.
Marie Dennis, 33, will faces charges of endangering the welfare of a child, resisting arrest and second-degree assault.
WCVB reports that police and fire crews had to break into the car to remove the children. The kids were taken to the hospital to be examined, and were released into the custody of a caregiver.
Heatstroke is the No. 1 cause of non-crash, vehicle-related deaths for children ages 14 and under, according to Safe Kids Worldwide. It takes only 10 minutes for a car to heat up by 20 degrees.
Follow Metro Boston on Twitter:@MetroBOS