MEMPHIS, Tenn. — “This is an emergency message …”

Many were woken up Saturday night to a phone call and text from the Memphis Police Department alerting the city of a manhunt to find Mavis Christian Jr., the man accused of shooting five females and killing four before he was found dead overnight.

It was the voice of Memphis Alerts system, a relatively new system MPD says alerts the public of critical events, severe weather, and any incident that could be a danger to the general public.

How does this emergency alert system work and when does MPD use it?

The Memphis Alerts system was implemented this February, months after Ezekiel Kelly allegedly shot six people across the city, killing three in a shooting spree that gripped the city for hours.

At that time MPD had no way of alerting everyone that the city of Memphis was put on lockdown.

But how does MPD have your phone number? They say this system allows the City of Memphis to send messages to specific areas or even to the entire city.

MPD says, to make sure you receive alerts through text, calls, or email from the City of Memphis, you need to sign up at Memphisalerts.com