GM-GMC: gmc jimmy 1999, gmc jimmy, buzzer

Question
inserted key to start,buzzer sounded then nothing. can not remove key,no power.Is it possible security system is engaged?

Answer
There is no reason you shouldn't be able to remove the key as long as it is in park?!?  Try putting a battery charger on it to see if the key can be removed.  It is possible that the battery is dead and not allowing the shifter to be put into park fully.  If your shifter is not in park you will not be able to remove the key.
hope this helps