yum fails to install other correct rpms when passing multiple rpms

i was installing multiple rpms (kernel, pango, curl, nss, python-perf, etc.) at once by passing all the rpms in single command : "yum install pkg1 pkg2 pkg3 ..pkgN". Except pkg1, all other were correct. pkg1 had some problem. when i tried to install, yum failed and didn't install any packages. But when i removed pkg1 from the list then yum installed all the packages.
Doesn't yum install the correct packages but throw error for the failures when passing multiple packages at once? Or yum mulitple package installation command internally installs the packages one-by-one? Please clarify. I'm working on security vulnerabilities patching. So want to fix all the issues at one go.