on lockdown

1. Having movements restricted inside a particular building or area because of some current or imminent threat. The entire 40-story building has been on lockdown while federal agents deal with the hostage crisis. The prison remained on lockdown for nearly 48 hours while the guards attempted to suppress the riot and regain control.

2. Confined to one's home or immediate vicinity for a certain period of time as a means of preventing the spread of a dangerous disease. During the pandemic, our city was on lockdown for weeks to try to limit the spread of the coronavirus. The entire region was put on strict lockdown in order to contain an outbreak of Ebola.