LONDON, July 2 (Reuters) - Four people died in Spain, two in France and two in Italy as an early summer heatwave continued to grip much of Europe on Wednesday, triggering health alerts and forest fires and forcing the closure of a nuclear reactor at a Swiss power plant.

The heat was so expansive that mountaintops, including the French Alps, that are usually frozen from snowpack saw record temperatures. Heat records were set for June in Spain and Portugal.

PARIS -- Europe sizzled in its first major heat wave of the summer on Tuesday, as Barcelona recorded its hottest June in over a century and the summit of Paris’ iconic Eiffel Tower was closed to visitors.