Let's take a look at where they are. I pinpointed two IRGC facilities in east of Tehran, within Ghasre Firouzeh area, through Google earth satellite pictures. And those are places where these poor guys might be held.
The first image shows the entire Ghasre Firouzeh military complex where Iranian armed forces from regular army, air force, IRGC and Police forces are located and have their own bases and buildings. The area also houses the biggest military hospital of the middle east belonging to Air Force and built by Americans in late 70s. It was once a restricted area until mid 1990s and then Tehran was booming so fast that the government had to make some highways around this area and started opening it up to ease the heavy traffic of eastern part of Tehran. Ghasre Firouzeh or Turquoise Palace has taken its name from a Qajarid era palace that is located in that area. Check this image
The Iraqi POWs of 1980s had been settled in a stadium and military prison of Ghasre Firouzeh area until 1991-92.
The 2nd image shows us where IRGC Mechanized Infantry Division is located. And the third one showing us the IRGC main HQ. These are heavily defended areas and armed guards watch over high watch-towers 24/7. Moreover, east of Tehran has always been a place for military facilities. IRGC missile manufacturing factory is just couple of miles away from this area. [Another IRGC HQ photo and here is a better one]
The entire incident will be getting more interesting as days go by. Just let's hope they are released soon...
News flash: Iranians shot at Americans