A 3-year-old District Heights boy was found critically injured Tuesday night as the result of what Prince George's County police called a severe beating. The child's mother and a 15-year-old babysitter were arrested on child abuse charges yesterday.

The child, Isaac McComb, was reported in critical but stable condition last night at Children's Hospital. Police said he suffered a severe head injury and had been beaten, kicked, choked, thrown against a wall and had had boiling water poured on his back.

Police said the child was left in the care of the teen-age boy from 8 p.m. Monday until 6 p.m. Tuesday. The babysitter's foster mother called an ambulance for the child after the 15-year-old called her to the McComb apartment at 6811 Atwood St., police said.

Before being taken away in the ambulance, the child suffered cardiac arrest and was revived by an employe of the Potomac Electric Power Co. who was in the area and administered resuscitation, according to police. The child was taken to Prince George's General Hospital before being flown by helicopter to Children's Hospital.

The babysitter, charged as a juvenile, was held at the Thomas J. Waxter Childrens' Center in Laurel. Police said Vanessa McComb, 21, the child's mother, was questioned when she returned home about 9 p.m. Tuesday and later was arrested and jailed without bond. Her young daughter was taken into protective custody, police said.