Officials are trying to solve a mystery in one eastern Kentucky city. They want to know how petroleum ended up in its water system

Whitesburg city officials say they discovered the problem earlier this week.

They're waiting on test results to see how much petroleum made it into the water system. They still don't know where it came from.

Customers are being told not to drink or cook with the water for now.

All Letcher County schools were closed on Wednesday because of the problem.