Only if the the guns are loaded. If they are unloaded and locked in the trunk, you are fine. If you have a loaded handgun and have a carry permit that is recognized by the state of Indiana, you are fine with it being accessible.
Firearms Owners’ Protection Act, or FOPA, protects those who are transporting firearms for lawful purposes from local restrictions which would otherwise prohibit passage. But it isn't completely true, see below.
http://www.nraila.org/gun-laws/articles/2010/guide-to-the-interstate-transportation.aspx