BRUSSELS (AP) — European Union leaders were reeling Friday after Britain's shock vote to leave the bloc plunged the EU into deep uncertainty, not least over how to negotiate the unprecedented departure of a member state. Top EU officials tried to put on a brave face as the European enterprise — already wracked by economic woes, Greece's shaky future in the euro and Europe's inability to manage the refugee emergency — came face to face with yet another existential challenge. European Parliament President Martin Schulz announced the assembly would hold an emergency session Tuesday morning, hours before a two-day summit of presidents and prime ministers, to debate the next steps. [...] European Commission President Jean-Claude Juncker was hosting talks with Tusk, Schulz and Dutch Prime Minister Mark Rutte, whose country holds the EU's rotating presidency, to try to navigate the way ahead through what are uncharted waters.