Complex sentence: A fire had broken out earlier on 19 January 1917, and efforts to stop it were under way when it ignited the TNT at 6:52 PM, instantly destroying the plant and nearby buildings, including the Silvertown Fire Station.
Split into simpler sentences: A fire had broken out earlier on 19 January 1917. The plant was destroyed instantly, as were many nearby buildings, including the Silvertown Fire Station.