Nine people were shot at a gathering in Fresno on Sunday evening after a family had gathered to watch football, police said. Authorities said some of those shot were killed, but did not provide a specific number.

A suspect sneaked into the back of the home and opened fire on the people who had gathered there, according to Fresno Police Lt. Bill Dooley.

The shoot took place at about 6 p.m. local time.

The shooter was able to escape and police do not know their identity, Dooley said. It is, however, possible the person was known to the victims.

Multiple victims were transported to the hospital, including some in critical condition, police said.

Dozens of emergency vehicles were on the scene in southeast Fresno, near the city’s airport.

The Federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is sending a team to help investigate the shooting.

ABC News’ Marilyn Heck and Alex Stone contributed to this report.

This is a developing story. Check back for updates.