Officers said they were dispatched to the 1000 block of Walnut Street regarding an assault at 12:09 p.m. on Saturday.
When the officers arrived they contacted 74 year old Robert Salisbury.
Salisbury said he was helping his 25 year-old grandson Thomas Browninghoagland, move some of his belongings from a home.
While moving, Browninghoagland became upset with his grandfather and threw a claw hammer at him.
The hammer allegedly struck Salisbury in the abdomen, which caused some bruising and swelling.
Salisbury declined medical attention at the scene.
Browinghoagland was arrested for assault with a deadly weapon and elder abuse.
He was booked into the Tehama County Jail on $80,000 bail.