Guesses

Mark was the first to wake up when he heard the knocking sound from the door. Getting up, he slowly made his way out of the room and towards the door. Everyone else was still asleep, taking a rest. He took out his gun and was alert. 

He peeked through the hole and noticed it was the same soldier who escorted them to the room earlier that day. Slightly relaxing, he kept the gun back and opened the door. 

"Hope you guys had a good rest. They will serve dinner in an hour. Be sure to be there on time." And left before Mark could even reply. 

Closing the door, Mark noticed the time was already 6 in the evening. The flat only had 4 working lights. One in each room and two in the living room. Turning on the lights, he went back into the room he slept and said while turning on the light, "David, Kevin, wake up."