Spree Murder is defined as a single event with two or more locations and no emotional cooling-off period between murders.
Serial murder is defined as three or more separate events in three or more separate locations with an emotional cooling-off period between homicides.
In addition the manual doesn't have a listing (1997 edition) for terrorism but the closest classification for these events is
126: NONSPECIFIC-MOTIVE KILLING
A nonspecific-motive killing pertains to a homicide that appears irrational and is committed for a reason known only to the offender. It subsequently may be defined and categorized after more extensive investigation in to the offender's background.Victimology. The victims of a nonspecific homicide are random, with no direct relationship between victim and offender.
What's notable about these shootings is that, if the eyewitnesses are correct, there are two men working together presumably one being the shooter and one being the driver. They would have to share the same ideology. Which indicates a more coordinated plan and hence more specific.
So if the victims are random but the attack is coordinated and continues after the cooling-off period it appears as if this is a serial event. Then again the more obvious explanation is terrorism. Maybe the "new" manual will update the classifications to include terrorism.