EL MIRAGE, Ariz. -- El Mirage police are still searching for a dog that attacked a 3-year-old boy Sunday night, authorities said.

Cristina Ortega and her 3-year old son Ismael were out back at a neighbor's house Sunday night on West Columbine Drive celebrating Father's Day when a brown and white pit bull wandered into the back yard.

The dog grabbed the boy by the back of his head and would not let go.

The boy's father and two other men were eventually able to free the boy. The boy's father was slightly injured on the arm in the process.

"It was horrible," Ortega said. "It’s like the kids were all screaming they were screaming their heads off and I was trying to yank, you know, grab my child and I could just here the dog ripping him to pieces."

The boy's thumb was almost bitten off and a large chunk of his scalp at the back of his head was torn away. Doctors were able to stitch his thumb and staple his scalp. The boy is expected to make a full recovery, however, he is undergoing a series of rabies shots as a precaution.

El Mirage police officers and Maricopa County Animal Control officers have been searching for the dog since the attack. So far, they have been unable to locate the dog.

Neighbors told police that they had seen a similar dog roaming the street in the mornings, and other neighbors said the dog may be living in the nearby Agua Fria River bed.

Police ask anyone with information about the dog to call 911 or the El Mirage Police Department at 623-433-9500.