Officials blamed recent rains and an underground sewage flow from a ruptured main for the tragedy.
I'm not thinking so.
Ruptured main? 330 feet deep? C'mon, even if they ran the main 33' deep, it's not going to erode 300' deep. Besides, where is the broken pipe sticking out of the sides of the hole? Looks to me like they unwittingly built the town over an underground chasm and the roof finally gave out.
My aunt was an archaeologist in the Yucatan, and these naturally occurring sinkholes are all over the place. They're called cenotes. The ancient inhabitants used to throw maidens into them as sacrifices.
There have been several articles in National Geographic from the 1960s forward. A recent one showed photographs of a cenote that's connected with the ocean by underground passages. Some (really brave and really stupid) scuba divers actually went through.