A Ukrainian tech company, Ajax Systems, deployed an app called Alarm designed to warn users of incoming air raids.
According to Jacob Soboroff of NBC News, the app can sound the warning before the traditional sirens on the streets.
A developer at Ajax Systems, Valentine Hrytsenko, says the app has reached four million downloads.
The usual air raid sirens sound when a government official pushes a button.
That same official now pushes a second button that triggers the app on smartphones.
Business Insider reports the app is available across Ukraine and proves especially useful in rural parts of the country where air raid sirens are not always present.
Hrytsenko added the team would continue to develop the app to give warnings for other attacks such as chemical or biological.
Ajax Systems specializes in cybersecurity and Hrytsenko claims it is prepared to prevent any cyberattacks.