Group-Panel Interviews

Under most circumstances the interviewee is given prior information in case he/she is going to be interviewed by more than one person (Panel Interview); but such information being passed onto you is not a compulsion. It could be that the panel of interviewers may or may not have a pre-planned list of questions. There is a barrage of questions that will be fired at you, ensure that you are not in a situation where you are juggling between which ones to answer and who asked which question.
Make an eye contact with the one who you will be answering and the start with your response. There is no need to make hurried answers, rather speak as you normally would and ensure that each one of the interviewers are listening to you so your points, answers, achievements, experience and relevant skills are known to all at the same time.
Agreed that facing a panel interview is tough but if they are making things hard for you its basically because they would like to see you react in group sittings as well as see how well you perform. Relax, smile, and do your best!

Both these interviews can take hours to come to an end. There will be various task and questions laid out to the group or an individual and performance will be judged.