Name of a TV Show I'm looking for?

Hi, I'm a really huge fan of zombies/apocalypse/infected movies and tv shows. I remember a tv show or movie I've briefly seen around 5-8 years ago that was aired on tv. Unfortunately I never caught the title. What I remember is something like there is a group of people locked in a building and there is some sort of infection like the rage virus from 28 days later. It might have been futuristic so I might have seen it on like Syfy or maybe HBO though I might not have been totally sure. There were people with guns and it was very dark and I remember flashlights and that the infected were fast like 28 days later maybe. I think one of the main characters got bitten and tried to hide it maybe?? Like I said it was a long time ago and I just have few images of it in my head. Please try to help by finding out the title because I really want to watch it and I remember it was pretty good as it was exciting and somewhat scary at the time. Thank you!