WOODBURY - A National Grid system error left some customers with bills of nearly $10,000, the company says.

National Grid says approximately 1,400 customers across the Island got sky-high bills this year of anywhere from $4,000 to almost $10,000.

National Grid blames the astronomical bills on electronic "smart meters" that were improperly programmed. It says there was also a billing glitch when it switched away from working with LIPA.

The utility company says it has identified the majority of customers it overcharged, and is working to correct the errors.

Customers who believe they have been overcharged are asked to immediately call the company, even if they have already paid the bill or just have questions.