Use the stairs to get to the lower floor. Open a single door. I would recommend zooming in the view. You should be able to spot a single terrorist in a distance (#1). Kill him. Start moving forward. It would be best if you'd let your teammates take part in these fights. You will come across a large are that's occupied by hostile forces (#2). You might want to consider using your night vision goggles, although this is not necessary.
Keep heading towards the RIGHT entrance. It leads to a new section of the complex. Be careful, though. The entrance might be guarded by one of the terrorists (#1). He will be hiding on your left. Kill him. Open the next door. You will find yourself in a large cafeteria. Bear in mind that it's occupied by a large group of enemy soldiers. Order your men to defend this positoon (#2). They will automatically use nearby objects for cover. You might want to help them in taking out some of the terrorists.
Once you've taken care of the nearby hostiles leave the rest of the team behind. Start moving towards the right corridor (#1). You should be able to reach a central part of the cafeteria within a few seconds. Duck behind one of the pillars. This is a good spot to take care of the remaining terrorists (#2). After that, gather the rest of the team around you.
Make sure that the area is clear. Start moving forward. At about half way through, turn right and choose a small corridor (#1). It leads to a new section of the complex. You have to go there now (with the whole team). There aren't any enemies in the vicinity, so you can as well start running towards your current destination. Stop the moment you've reached metal doors (#1). Make sure you have reloaded your weapon!!
First of all, I would recommend taking down a single terrorist (#1). He is hiding by one of the beds located on the left side of the room. The area is occupied by a large group of enemy soldiers. I would recommend throwing a couple of grenades inside. Storm the place with the rest of the squad (#2). Watch out for the additional terrorist. He can also be found by one of the beds.
Exit the room and turn right. You will come across a new terrorist (#1). Kill him. Keep moving towards your next destination. There's only one path leading to the basement, so you can't get lost. Be sure to use the stairs to get down there. Order your team to stop the moment you've reached a small door (#2). You have to pick a lock in order to reach the morgue section.
You are getting closer to one of the main objectives of this mission. Open the door carefully. DON'T enter the new area just yet! I would recommend that you hold your position for now. Start shooting at visible enemy soldiers (#1). Make sure that most of them are gone. Enter this room with the whole team. Start moving forward. You'll probably encounter some additional units along the way (#2). Remember to use all visible objects (pillars, machines...) for extra cover. You should be able to reach a new door within a few seconds.
Open this new door. Be careful! There are some new terrorists on your left (#1). If you're lucky, you should be able to surprise most of them. Enter this new corridor. There's a small room on your right. Go there now. Be careful, though. There's at least one enemy soldier here. He will be standing by the table. Kill him. As you've probably noticed, one of the hostages was being held in this room (#2). He must join the rest of the team. Get back to the main corridor.
This time you will have to go to opposite room (located on your left). It's going to be guarded by two additional terrorists (#1). You might want to consider opening the door carefully. Thanks to that, you should be able to surprise at least one of them. Rescue the second hostage. Now you must go back to the upper floor. Start moving. Thankfully, there aren't any new enemies in that area. Once again, you will have to use nearby stairs (#2). After that, wait for the rest of the team (including the hostages) to show up.
Lean out CAREFULLY. There are some new terrorists in a nearby room (#1). Just as before, you've got to be very careful. Some of them will probably be hiding. You have to remember that. One of these terrorists should be located on your left. Head on to the opposite end of this room (#2). Reload your weapon!
Once again, I would recommend that you lean out in order to kill some of the nearby terrorists. Most of them will be standing by the metal door (#1). Start moving forward. You've got to be very careful!! There's only one more thing to do here. You will have to clear out one of the surrounding rooms (#2). Remember to use all possible cover. Just as before, some of the terrorists may still be hiding in that area. It would also be wise to let your teammates join you in these fights. They won't have to protect the hostages anymore.
Make sure that the area is clear before you decide to move the hostages to this location. Gather everyone at the extraction zone (#2). A short cut-scene should appear on your screen shortly (#2). After that, this mission will come to an end.