This attack at a refinery.
Not sure a refinery is the target. This occurred in a parking facility where workers park and shuttle service is used to get them to mulitple work facilities in the area.
snip
The shooting occurred around 5:30 a.m. in a parking lot used by workers in an area of manufacturing plants and refineries along the Mississippi River........
Unofficial reports indicate that one suspect has been captured and another is still being sought.
http://www.nola.com/crime/index.ssf/2012/08/2_st_john_parish_sheriffs_depu.html
Almost all such parking lots already have no guns/no drugs signs.