All builds are stuck in queue

All builds on multiple repositories in our organization have been stuck for more than 3 hours. Restarting the builds doesn’t solve the issue.
The runners are CircleCI runners, not self-hosted.

CircleCI status page says that all systems are operational.
How can this issue be resolved?

:wave: Hi @JekRock,

The situation you’re describing suggests that, at the time, your organization had reached the plan’s concurrency limit.

Note that if a job is configured to execute parallel runs, the job won’t start until at least as many containers as the parallelism value are available.

Please see this blog post from our Technical Community Manager to learn more about concurrency and parallelism in CircleCI.