'This is so hard': Father's anguished announcement his son was killed in shooting

The father of one of the people killed during a shooting in California has sobbed his way through an emotional press conference announcing his son's death.

A gunman killed 12 people when he opened fire at a country bar in Thousand Oaks Island, California during a music night for university students.

Eleven bar attendees were killed, along with Ventura County Sheriff's Deputy Sergeant Ron Helus.

Jason Coffman's son was among the fatalities, and Mr Coffman emotionally told reporters about the shooting's effect on him.

"His name was Cody Coffman - my first born son. Only him and I know how much I love and... miss [him]. Oh God this is so hard. Oh son I love you so much," Mr Coffman said through tears.

"Cody was the big brother that my kids need. I have a daughter coming on the 29th of this month. He was so excited to have his first sister and now she will never know."

Mr Coffman said his son, who was 22, had been talking to recruiters and was looking at joining the army.

He said he could not believe the shooting had happened and he didn't know what to say to other families who were going through the same situation has him.

He shared his last words to his son with reporters, a simple "I love you".

"First thing I said was please don't drink and drive. The last thing I said was son, I love you. That was the last thing I said."