It happened before midnight Wednesday at a home on Hughes near South Avenue, just southwest of Easton.
Officials say 27-year-old Christopher Chacon stabbed and killed his 73-year-old grandfather, Jose Espinoza, and injured three other family members.
1 killed, multiple injured after stabbing in Fresno County: Deputies
The motive for the stabbings is still under investigation.
Chacon was arrested and booked into the Fresno County Jail.
A GoFundMe account has been set up to help Espinoza's family.
For news updates, follow Amanda Aguilar on Facebook, Twitter and Instagram.
For news updates, follow Elisa Navarro on Facebook, Twitter and Instagram.