[take|hold] hostage

to keep someone as a captive with the intention of making demands or taking advantage

Terrorists took a group of tourists hostage in a foreign country.
Negotiators worked to secure the release of the journalists held hostage in a war zone.
The criminal held the family hostage in their own home during a home invasion.
Authorities are trained to handle situations where individuals are held hostage to minimize harm and secure their release.
The hijackers held the airplane passengers hostage to make political demands.