I have a 3rd floor unit in an apartment building. My kitchen sink drain was running slow. The plumber ran a 13/32” cable 40 feet through my kitchen line to clear blockage. Two weeks later the two apartments below mine (both vacant at the time) were discovered with damages: the 2nd floor unit (which is the one below mine) had water coming out of their kitchen sink and spilling on the kitchen floor, while the 1st floor unit had a caved-in ceiling. What is the possible explanation for this scenario? Am I right in assuming the clog must have been below the 2nd floor unit level?