H1B extension after expiry in USA

My Visa & I94 is expiring by 30-Sep-2013 and im currently in USA, i have applied new LCA on 26-Sep and im going to file petition for extension by 4-OCT-2013. Is it valid to do it? .

is it valid to stay in US after Sep-30 if LCA intiation is complete before sep-30

Please help me that