Natural selection 2- Locked in a closet.

You know how everyone says they need to get out of a closet?
Turns out its better to stay in one.

When the Aliens arrived, They were able to take over the entire facility in a matter of moments. Clearing out every single staff member and scientist they came across and turned them into green slush.
These three men were a just a few combat oriented soldiers with proper equipment available on them making them the sole survivors of the facility.
They were able to send out a Distress call and then barricade themselves in a supply locker with Food, ammo, and medical supplies.
There they await rescue by their fellow marines.

Their objective is to survive until then.