White students at a south Mississippi high school put a noose around the neck of a black student and "yanked backward", a civil rights group has claimed.

Twelve vehicles were swallowed when a 120m-long section of an outdoor parking lot caved in outside a Mississippi pancake house that had only been open for a few days.

Looks like the car park was hungry too.

A professor has been shot dead in his office at a US university and the campus remained on lockdown after reports of a gunman on the loose.

Update at 9.30pm: Police has named university employee Shannon Lamb as a ``person of interest'' in the shooting of history professor Ethan Schmidt.

A US judge has temporarily blocked the state of Mississippi from carrying out executions.