A pack of pit bulls yanked a 4-year-old Detroit boy from his mother, dragged him away and mauled him to death Wednesday, police said.

The boy died from his injuries after the attack in his neighborhood. Police killed three dogs and had a fourth pit bull in custody, Sgt. Cassandra Lewis said.

The attack occurred while the boy was walking with his mother. The dogs crawled through a gap at the bottom of a fence and pounced.

“The mother tried to fight the dogs off,” Police Chief James Craig said. “What’s telling in this scenario (is) the viciousness of these animals, the fact that they removed this child from the mother’s grasp.”

A witness, Nyasha Reid, said the mother screamed, “They got my baby.”

Reid and others called 911. Neighbors yelled at the dogs and used a brick and club to try to free the boy.

“The cop had to open fire to at least get the dogs off the baby,” said another witness, Yolanda Samuels.

The boy’s name was not released, nor was the name of the dogs’ 41-year-old owner. Police said he’s cooperating.

“It’s pretty much an open-and-shut case,” Lewis said. “We know who the dogs belong to.”