Complex sentence: The spill followed an explosion on a drilling rig leased by BP, the British oil company, and led to the release of over four million barrels of oil into the Gulf of Mexico, near the coast of Louisiana in the United States.
Split into simpler sentences: The spill followed an explosion on a drilling rig leased by BP, the British oil company. Over four million barrels of oil were released into the Gulf of Mexico, near the coast of Louisiana in the United States.