Parts of California's Silicon Valley were left without phone service Thursday morning after four or five fiber-optic cables were cut in south San Jose, the Mercury News reported.

The widespread outage disrupted 911 emergency services, land lines, cell phones and Internet access for Verizon customers in Morgan Hill, Gilroy, San Martin and Santa Cruz County, police told the newspaper.

Police said they are investigating whether someone sabotaged the cables, because it appears a manhole was opened and someone climbed down 8 to 10 feet to cut the cable, the newspaper reported.

Service is expected to be fully restored by Thursday evening.

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