Because there have been four mass killings in the last week, depending how you count these things, USA Today has produced an interactive database which will sort killings by type of killings, state, number of victims, weapon, and a couple of other factors, but NOT race and immigration status.

Explore the data on U.S. mass killings since 2006
USATODAY 12:05 p.m. EDT September 19, 2013
Mass killings database

Since 2006, more than 200 mass killings in the U.S.

Mass killings — defined by the FBI as four or more victims, not including the killer — have occurred across the U.S. at the rate of about one every two weeks since 2006. Explore mass killings by location, type and method.

Click here, or on the screenshot below to look at it.

The largest number is people snapping and killing their whole families. Another large number of them are armed robberies, like the Lane Bryant killings which are shown on the screenshot. In Tinley Park, Illinois, a black man herded six women in a clothing store into the back room, and shot all of them. Five died, but one survived, so we have description—which isn't mentioned by USA Today.

For the record, the four mass killings this week were committed by one white guy, killed his family, one white guy, killed his neighbors, one crazy Chinese immigrant (Ming Dong Chen, already covered by Peter Brimelow) and one black guy, Charles Brownlow, 36, who is basically a Willie Horton type and who ran amok, killing five  people,  in four incidents, and setting fire the house of one of his victims.

Here's a picture of Brownlow:

Here's a picture of Mingdong Chen: