On its status dashboard, Google said at 1605 Pacific time (9.05am AEST 3 July): "The disruptions with Google Cloud Networking and Load Balancing have been root caused to physical damage to multiple concurrent fibre bundles serving network paths in us-east1, and we expect a full resolution within the next 24 hours.
"In the meantime, we are electively re-routing traffic to ensure that customers' services will continue to operate reliably until the affected fibre paths are repaired. Some customers may observe elevated latency during this period.
The company said it would provide another status update as warranted or by Wednesday 12 noon (5am AEST 4 July).
This is the second major outage to hit Google's services in as many months.
In June, the company's services were affected by serious networking issues in the eastern part of the United States, affecting multiple services in Google Cloud, G Suite and YouTube.
Gmail, Google Calendar, Drive, Docs, Sheets, Slides, Sites, Groups, Hangouts (plus its Chat and Meet), Vault, Forms, Keep, Tasks and Voice were all affected.
Update, 5.45am AEST, 4 July: A Google spokesperson said the disruption with Google Cloud Networking and Load Balancing had been resolved as of 07.35 Pacific time 3 July (0.35am 4 July AEST).
"The physical damage to the fibre bundles serving some network paths in us-east1 have been repaired, and we have removed the elective routing mitigations previously in place and returned to normal routing in the region," the spokesperson said.
"We will perform an internal review of the incident and make appropriate improvements so that our customers continue to be able to operate reliably during incidents such as this."