This time, it was a worker in a Kansas factory who shot lots of people at the plant and other locations in the small Kansas town, killing some of them, before he was killed by a cop. Four people, including the gunman were killed, and fourteen people were injured, ten critically.
UPDATE February 26, 2016: Shooter Cedric Ford, who grew up in Miami, Florida, launched his shooting spree about an hour and a half after he was served by sheriff's deputies with a protection order. Ford had a criminal record including multiple arrests and at least one prior felony conviction over the course of the last decade and a half, so the handgun and assault rifle he used were almost surely in his possession in violation of federal laws barring felons from being in possession of firearms (usually with a ten year minimum sentence). END UPDATE.
In between this and the last mass shooting, in Kalamazoo, Michigan last Saturday, an anti-government activist previously associated with the Occupy Movement and the Green Party, shot three sheriff's deputies who were evicting him from his Bailey, Colorado home (which had been foreclosed upon long before then), killing one of them and injuring the other two (one critically) before being shot and killed by the officers.