RNZ understands repairs will continue into the night after in an attempt to get thousands of homes and businesses in the Kaipara District back online.
A Spark spokeswoman said the damaged fibre-optic cable contained a mixture of Spark and Chorus cables, leading to broadband outages across multiple providers.
She said Chorus technicians were on site and making progress on repairs. As of 6pm one of the damaged cables had been repaired.
The spokeswoman said broadband customers could make use of Spark's outage assist service, which offered free mobile data while fibre connections were down.
A Northpower spokesperson said the cable supplied broadband to all customers in Dargaville, Ruawai, Paparoa and Maungaturoto.
More than 2070 customers were affected, with many businesses forced to close or switch to cash-only transactions.
Northpower said the damage was caused by a digger pulling up the main fibre cable.
Dargaville resident Rose Dixon said there were huge queues at the town's supermarket because Eftpos was down and customers without sufficient cash had to fill in credit notes instead.
RNZ understands repairs to the cable will continue into the night. There is currently no estimate for the restoration time.
Chorus could not be contacted for comment.
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