At one point, the suspected drug traffickers shot at one another as their sport utility vehicles sped down a busy six-lane boulevard.
All of the dead are believed to be drug traffickers, possibly rival members of the same cartel. Eight suspects and one federal police officer were injured.
Police have recovered 21 vehicles, many with bullet holes or American license plates, and 54 guns.
Police say the first shootout claimed seven victims. Three subsequent gunbattles - one outside a hospital - claimed five more. The body of a man police believe to be the 13th victim turned up at a city hospital.