NTSB: No proof yet of gas leak complaints before deadly blast in San Francisco suburb

Federal investigators are asking for the public's help to determine whether a gas line in a San Francisco suburb was leaking before a deadly fireball destroyed nearly 50 homes.

Christopher Hart of the National Transportation Safety Board says investigators have not yet seen any record of gas leak complaints before Thursday's explosion in a San Bruno neighborhood.

Some residents have said they smelled gas in the days leading up to the blast.

Officials are asking those people — especially anyone who called Pacific Gas and Electric about the problem — to tell officials.

Hart also says investigators want to talk to residents who noticed dead vegetation around the rupture spot, which can be a sign of a leak.

Four people have been confirmed dead in Thursday's blast, and four remain missing.

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Burke reported from Fresno, Calif.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

SAN BRUNO, Calif. (AP) — Federal investigators are asking for the public's help in determining how a gas line in a San Francisco suburb was able to rupture into a deadly fireball.

The National Transportation Safety Board's Christopher Hart says investigators have not yet seen any record of gas leak complaints before last week's explosion in a San Bruno neighborhood.

Some residents have said they smelled gas in the days leading up to the blast.

Officials are asking those people — especially anyone who called Pacific Gas and Electric about the problem — to tell officials.

Hart also says investigators want to talk to residents who noticed dead vegetation around the rupture spot, which can be a sign of a leak.

Four people have been confirmed dead in Thursday's blast, and four remain missing.