LIPA spokesman Mark Gross said a transmission line that went out in East Hampton caused the outages.
The line was tripped at about 11 a.m., affecting less than 10,000 homes and businesses, about 1 percent of LIPA's customers, Gross said.
By 12:20 p.m., all of the affected customers were back on line, Gross said.
Gross said the cause of the transmission trip was being investigated.
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