There are at least two sides to every story, so check it out. Stick to the details of the situation - what actually happened. If possible, come to some agreement among those involved. Summarize what has been said to make sure that you have the story right. If there are differences of opinion, summarize each child's opinion.
People often see things differently.
Recognizing each child's view encourages her or him to maintain honesty and integrity. Stating that Ricky knocked the building down is not blaming - it is stating a fact. Look for information which may explain why Ricky was destructive. For example, comments may reflect a rejection of Ricky's involvement in building. In that case, it is time to talk about Ricky's feelings of being left out or rejected.