Sci-Fi Movie about Zombie Inmates

I have been looking for the title of a zombie movie I saw on television (i think it was on Sci-Fi). It was about some guy who was infected with some disease and then was taken into a huge prison. Somehow the infection spread and all the inmates got the disease and became zombies.

The warden had his family there at the prison and the remaining guards were trying to protect the warden's family and some scientists. I remember in the end there is a helicopter hovering over the prison courtyard and one of the surviving scientists runs out into the yard to get the helicopters attention, then she gets shot and killed by a sharpshooter in the chopper.

It's a newer movie, I'd say around 2002-2006 somewhere in there. Any ideas on what it is?

Thanks!