Ambulances were on the scene.

An unidentified source told The Mail, a Barrow-in-Furness-based publication known previously as the North-West Evening Mail, that staff had been evacuated after a warning about a bomb on an Astute-class nuclear attack submarine.

https://timesofislamabad.com/10-Apr-2019/bomb-threat-in-britain-nuclear-submarine-dock-complex-closed