US energy giant PG&E was hit with a $1.6 billion fine Thursday over the deadly 2010 explosion in California which left eight people dead, authorities said.
The California Public Utilities Commission (CPUC) said the fine was the heaviest ever imposed by authorities in the state.
The devastating September 2010 pipeline explosion near the town of San Bruno, close to San Francisco, destroyed around 30 homes.
"PG&E failed to uphold the public's trust. The CPUC failed to keep vigilant. Lives were lost. Numerous people were injured. Homes were destroyed. We must do everything we can to ensure that nothing like this happens again," CPUC chief Michael Picker said in a statement.
Part of the fine will be used to upgrade the network of pipelines across California including PG&E pipelines.
PG&E said in a separate statement that the "lessons" of the San Bruno explosion would not be forgotten.
It added that it had already distributed more than $500 million to victims of the blast and their families, established a $50 million fund for the city of San Bruno and contributed more than $70 million towards rebuilding in the town.
PG&E -- the Pacific Gas and Electric Company -- distributes energy to around 16 million customers throughout north and central California.
PG&E stock closed 1.55 percent lower on Wall Street Thursday, ending the day at $52.78.