Nashville school shooting - Shooter suffered from emotional disorder: Police

She was an ex-student and had a collection of guns, but no motive established yet

NASHVILLE, Tennessee The former student of a Christian grade school in Nashville who killed three nine-year-olds and three adults in a shooting spree there was under a doctor's care for an "emotional disorder" and had amassed a collection of guns, the city's police chief said on Tuesday.

New details about assailant Audrey Elizabeth Hale, 28, emerged hours after police released a harrowing video showing officers storming the Covenant School in the midst of Monday's rampage and conducting a room-to-room search before confronting and fatally shooting Hale.

The authorities said they were still trying to pin down a motive as detectives pored over various writings and other evidence left by Hale.

Hale was armed with two assault-style weapons and a hand-gun, the latest in a long string of US mass shootings that have turned schools into killing zones and added fuel to a national debate over gun rights and regulations.

The three weapons used on Monday were among seven firearms that Hale had legally purchased in recent years from five Nashville-area stores, Metropolitan Nashville police chief John Drake told reporters on Tuesday.

Hale's own parents did not know that she possessed multiple firearms, mistakenly believing that she had owned just one gun, then sold it, Mr Drake said.