Four people were killed and six more were injured in a shooting at an NFL watch party in Fresno, Calif., Sunday evening, according to TMZ Sports. 

About three dozen friends and family members were in attendance at the backyard event and were watching the Sunday Night Football game between the Los Angeles Rams and Chicago Bears until multiple shooters entered the premises and began shooting.

"Everyone was watching football this evening when unknown suspects approached the residence, snuck into the backyard and opened fire," Fresno Police Lt. Bill Dooley said.

Police have called it a "targeted act of violence" and believe it could be retaliation for an incident earlier in the week.

The police have not yet made an arrest in the case or identified a suspect.