America has now endured 339 mass shootings so far this year, according to the Gun Violence Archive.

The US has grown accustomed to mass shootings in public places such as schools, shopping centres and churches.

Shootings are extremely rare in Japan, where gun ownership is tightly regulated and anyone seeking to own a gun must go through a rigorous vetting process.

Some of the victims were as young as five years old, reports say.

Biofire's gun can also be enabled by a fingerprint reader, one of several smart gun features designed to avoid accidental shootings by children, reduce suicides, protect police from gun grabs, or render lost and stolen guns useless.

Two victims were shot inside the store in what authorities said appeared to be a random act of violence, and a third was shot outside.

The al Qaeda-linked Islamist group claimed responsibility for two car bombs that exploded outside the education ministry in Somalia's capital Mogadishu, killing at least 120 people.

The attack shocked the country and prompted a government call for law enforcement agencies to tighten gun ownership rules and to crack down on drugs.

Three others were wounded in the shootings in Memphis, Tennessee.

Law enforcement officials have been roundly criticised for their handling of the rampage and especially for waiting more than an hour before confronting the shooter.

Congress has shown little inclination to outlaw assault weapons after a ban on such weapons expired in 2004, but Biden is hoping to use growing American outrage about mass shootings to lead to greater pressure on lawmakers to change their mind.

Emergency officials say around two dozen people, including children, were treated for gunshot injuries, with some in critical condition.