An eight-month-old boy is dead and his babysitter injured after the family dog turned on the baby in a vicious attack.

According to CBS Baltimore, the infant and his babysitter were at the boy’s Lusby, Maryland, home Thursday afternoon when the family’s pit bull began mauling the baby, pinning him to the living room floor, in what authorities believe was an unprovoked attack.

When the babysitter, a family friend, tried to intervene, the dog attacked her as well. Though emergency services arrived within a minute of her desperate 911 call, police told CBS Baltimore it was too late for the baby.

Deputies shot and killed the dog on the scene.

“They knew immediately the only way to stop that attack was to shoot that dog,” Calvert County Sheriff Mike Evans told the news station.

The deadly attack is “one of the worst tragedies our community has suffered in such a long time, it is almost unspeakable,” said Calvert County Commissioner Tom Hejl.

Police do not plan to file any charges in the fatal dog attack.