Published: Sep 28, 2012 6:15 AM EDT

MINNEAPOLIS (AP) - Authorities say a gunman killed four people inside a Minneapolis sign-making business before turning the weapon on himself.
 
Officers summoned Thursday afternoon by a 911 call discovered the victims' bodies shortly after arriving at Accent Signage Systems Inc. on the city's north side, police say.
 
Four other people were wounded, including three critically.
 
None of the victims' names has been released.
 
No details were released about the gunman, other than he was found dead from an apparent self-inflicted gunshot wound.