A mother was arrested Saturday on suspicion murder after she allegedly stabbed her 7-month-old son to death at a Northern California park, authorities said.

Officers responding to reports of a woman ramming her car into a rock wall at Del Valle Regional Park east of San Francisco found an empty and damaged Honda Civic with a baby seat in the back. When they searched the park, they saw the woman carrying a baby with multiple stab wounds, East Bay Regional Park District police Chief Timothy Anderson said.

"This is an extremely shocking case for us," Anderson said.

The mother also had what appeared to be self-inflicted injuries, he said.

A pocket knife was found at the scene.

The woman in her early 20s was arrested on suspicion of murder. Her name was not immediately released and was expected to be booked into jail Saturday night.

Anderson told reporters she may have suffered from depression.

The stabbing occurred in a remote part of Camp Arroyo, the site of a popular children's camp inside the 4,400-acre park south of Livermore, a suburb that's about 45 miles east of San Francisco.