Internet customers across a broad swath of the eastern U.S. suffered slow or faltering access Tuesday, with customers registering complaints about service from broadband providers Verizon Communications Inc. and Comcast Corp.

Verizon technicians and network staff were investigating the situation but couldn’t yet confirm what caused the problem or the extent of the disruption, a company spokesman said Tuesday.

DownDetector, a real-time monitoring service, showed a surge in reports of service interruptions Tuesday from those providers, with a spillover to popular websites like Google, YouTube and Zoom. The problems appeared to be concentrated on the East Coast.

The pandemic has made broadband outages especially difficult. High-speed internet connections have become a lifeline during the Covid-19 pandemic as millions of office staff, students, health-care professionals and others use broadband to work remotely.

Verizon’s problems also are ill-timed for a company that just reported disappointing results on Tuesday morning.

The carrier’s shares slipped as much as 3.4% to $56.46, marking its biggest intraday decline since March 2020.

In response to questions about the blackout, Verizon reported on Twitter that it suffered a cut in a fiber line in the Brooklyn area, without offering an estimated time of repair. User comments suggest the outage was widespread.

This article was provided by Bloomberg News.