By CBS3 Staff

POTTSTOWN, Pa. (CBS) — Additional properties around the house explosion in Pottstown have been deemed unsafe. Inspectors were back at the scene on Thursday.

There is still no official word on what caused the explosion that killed four children and their grandmother last week.

A number of agencies are involved in the investigation.

PECO says so far no evidence has been found that would suggest that its natural gas lines were the cause.