Donald Tusk, President of the European Council
"This is not a moment for hysterical reactions. Today on behalf of the 27 leaders I can say that we are determined to keep our unity as 27.
"Until the UK formally leaves the EU, EU law will continue to apply to and within the UK, and by this I mean rights, as well as obligations.
"All the procedures for the withdrawal of the UK from the EU are set out in the treaties. In order to discuss the details, I have offered an informal meeting of the 27 in the margins of the European council next week. I have also proposed we start a wider reflection of the future of our union.
"The past years have been the most difficult ones in the history of our union, but my father used to tell me: what doesn't kill you makes you stronger."
Martin Schulz, President of the European Parliament
"We respect the result. We have clarity for the UK to go its own way.
"Now is the time for us to behave seriously and responsibly. David Cameron has his responsibilities for his country, we have our responsibilities for the future of the EU. You can see what is happening to sterling on the markets. I don't want the same thing to happen to the euro. "