Customers reported disruptions on Verizon, Time Warner Cable and other networks, as crews scrambled to assess damage and begin restoring service.
"The storm surge from Hurricane Sandy has resulted in flooding at several Verizon Central Offices in Lower Manhattan, Queens, and Long Island causing power failures and rendering back-up power systems at these sites inoperable," Verizon said in a statement.
"While these sites are currently on battery power, the inevitable loss of power requires that all equipment at these sites be powered down to prevent damage."
Verizon did not say how many customers were affected, but added that anyone served by the damaged central offices will not have any internet or phone service.
"Verizon engineers continue to assess the damage at these locations and we will post updates as additional information is available," the company said.
Time Warner Cable customers also reported outages.
"It's cool, Time Warner. I don't need cable service right now," tweeted @_BornToDictate. "When I'm stuck at home. With absolutely nothing to do."
Time Warner said workers are examining the damage, but warned that restoring electricity takes precedence, so Time Warner services likely won't come back until the electricity does.
"TWC is in constant communication with @nycoem and our crews are across NYC and northern NJ to assess our network," the company tweeted. "Updates to follow."
Sprint and AT&T were also seeing outages Tuesday, representatives said.
"As we continue to closely monitor our wireline and wireless networks for service disruptions, we are experiencing some issues in areas heavily impacted by the storm," AT&T said in a statement. "We are in the initial stages of performing an on-the-ground assessment of our network for damage and crews will be working around the clock to restore service. We are deploying personnel and equipment as soon as it is safe to do so."
A Sprint spokeswoman said storm impacts include equipment damaged by flooding and debris.
"Given the ongoing weather conditions, we cannot provide a specific number of impacted customers, but we ask that they remain patient at this time and exercise caution in the aftermath of the recent events," Sprint said in a statement.