Four people were killed after a gunman opened fire at a high school 50 miles from Atlanta on Wednesday, in an incident being investigated by multiple law enforcement agencies.

Investigators continue to look for answers about what happened at Apalachee High School in Barrow County, Georgia, with county Sheriff Jud Smith telling reporters Wednesday that it would take “multiple days” to get a full understanding of the school shooting. Here is what we know about the school shooting at Apalachee High School.