Follow O'Neal, ignoring the battles outside; you're not in any danger for now. Go left at the end of the corridor, then search the small room pictured above to find the first Audio Log.
Resume the march to reach the stairs leading to the lower level. Make your way towards the above elevator and wait until takes you to a new floor; on the way you'll make a shocking discovery about the alien queen. Follow O'Neal and jump down when the platform is destroyed. Your life won't be in any danger here, so pay no attention to the queen and her attempts to break free. Use the stairs again. Soon you'll reach the exit.