Updated

The head of the National Transportation Safety Board is preparing to tour a neighborhood that was torched in a deadly gas pipeline explosion south of San Francisco.

Wednesday, Deborah Hersman will join Rep. Jackie Speier to visit the site of the September San Bruno explosion, which killed eight, injured dozens and destroyed 38 homes.

Hersman also will visit with Pacific Gas & Electric Co. officials and local authorities, as well as victims of the explosion and those who lost relatives in the accident.

NTSB investigators are still probing what caused the blast and are expected to issue a final report later this year.

Hersman has said the accident highlighted a pattern of recurring safety problems and suggested that regulations guiding the natural gas industry may require reforms.