SAN FRANCISCO (CBS SF) — Comcast was in explain-and-apologize mode after a widespread outage hit customers in the Seattle and San Francisco areas Monday night.

Internet and TV customers flooded social media with complaints when service went out around 8:30 p.m. Monday.  Comcast worked to resolve the issue, which it said was caused when “a piece of hardware in our backbone network failed.”

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The company was working to add DNS (domain name system) capacity to the networks in the affected areas.

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Comcast’s Washington team tweeted at the height of the problem that “Engineers investigating the issue now. We could say we apologize, & we do, but we know, we know, you want the Internet & we’re working it”

ComcastCares tweeted shortly before 11 p.m. Monday night that “Our engineers have restored service and everything should be working. We’re sorry for the inconvenience.”

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A service called Down Detector lets users who want to see if internet service is down in their area check for outage reports, but is only likely to be useful if internet service is available in the first place.