why is there water in 5 out of six cylinders but not in oil? on 2006 Chevrolet Trailblazer

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
was driving home and suddenly the rpms went really high on their own and then the car just died, will not crank over, no overheating, no check engine light, no loud noises, checked the oil, it looks dark and muddy but no sign of water, removed radiator cap and it looks like it melted on the inside and the radiator was almost empty, removed the spark plugs and starting from the front to the rear, all cylinders except the rear one had water in them, car has 120,000 miles on it
(1) Answer
(2) Comments
Will the engine turn by hand or with the starter , since the plugs were removed?
it wont move at al, someone told me that it got hydrolocked, ive never heard of that term, so not sure what it means
IF the spark plugs(all) are removed , it cannot be 'hydro-locked' , which means that with the plug(s) in the cylinder(s) and valves in closed position when the piston tries to reach top-dead-center , it cannot , if liquid is present , because it can't be compressed.From your description of the radiator , AND if it won't turn with the plugs removed , my best guess from 'on-line' world , is your engine seized due to melted main or rod bearings.