Hundreds of families evacuated by the Eaton Fire in Pasadena are being told their drinking water may be so toxic that even boiling cannot make it safe.

Officials in Pasadena are warning residents in the area of the Eaton Fire not to use their tap water. A do-not-drink order remains in effect for the evacuation zones.

Many residents fled the Altadena and Pasadena area due to the blaze that has consumed more than 10,000 acres with zero containment, according to Lisa Derderian, a city of Pasadena’s information officer. More than 800 people were at the evacuation center, Red Cross volunteers said Wednesday morning.