Emergency method to erease all data off a machine within seconds

Imagine you are carrying highly sensitive information with you, maybe on a mission in a war zone. You get in an ambush and quickly need to erase all the files before they fall in the wrong hands. This has to happen within seconds.

What devices are used for such operations, are there special hard drives which have a physical switch to erase all memory at once? I’m thinking of active storage devices, which lose all information once the power supply is separated. Or is it enough to have the proper software combined with a regular HDD or SSD?