SAN FRANCISCO (CBS SF/CNN) — Slack, a popular San Francisco-based workplace communication platform, confirmed early Monday that its service was interrupted for some users.

The service returned a few hours later. Unfortunately, the service disruption came as millions of remote workers were returning from a holiday break.

“Customers may experience issues connecting to Slack to loading channels at this time,” the company said. “Our team is on the case and we will keep you posted.”

At 10:30 am ET Monday, Slack’s status page showed that its messaging and connections functionality was being affected by a technical issue. By 12:10 am ET, Slack was back online.

Slack and similar services emerged as even more essential tools for office workers to stay connected to their colleagues after the pandemic forced countless businesses to shift to remote work almost overnight.

In a deal announced in December, business software pioneer Salesforce.com is buying Slack for $27.7 billion in a deal aimed at giving the two companies a better shot at competing against longtime industry powerhouse Microsoft.