( CNN ) -- A 17-year-old boy was among the seven people killed in a noon shootout Friday on the streets of Ciudad Juarez , Mexico , police said Saturday . The other victims were police officers , Mayor Jose Reyes Ferriz said Friday . Five were federal police officers and one was a female city police officer , all part of the joint police task force formed to combat drug violence in the border town . Another federal officer was gravely wounded , Reyes said , and a city officer was wounded but not with life-threatening injuries . A civilian was hit by shrapnel , but those injuries were also not serious , he said . Reyes said the incident began when two patrol cars , one from federal police and one from city police , stopped several people they had been investigating . Gunmen in at least two vehicles attacked the police convoy with weapons including AK-47s , he said . The federal police said the gunmen , who escaped in a gray Dodge Durango and a green Dodge Caravan , may have been drug dealers and that the attack may have been in response to several recent arrests in Juarez , including that of eight people apprehended Thursday for possession of weapons , drugs and a stolen van . The mayor said it was n't immediately clear why the police had stopped the people or whether the incident was drug related . Investigators are treating the incident `` as a direct attack on police officers , '' he said . Federal police launched an aerial search for the gunmen 's vehicles , but there have been no arrests . Reyes said at a meeting with federal police that he was ordering an increase of patrol cars so there will be three or four cars per location . About 800 police cars now patrol the city , Reyes said . The city police force consists of 3,000 officers , bolstered by 5,000 federal officers . Ciudad Juarez is the most violent city in the nation , with more than 2,600 drug-related deaths in 2009 . No official numbers are available , but more than 400 killings have been reported by local media this year . The city , long the focal point of President Felipe Calderon 's battle against drug cartels , came to renewed prominence after the January 31 killings of 15 people , most of them students with no links to organized crime . The massacre sparked outrage throughout Mexico and drew worldwide attention . In another incident that drew widespread attention , three people associated with the U.S. Consulate in Juarez were gunned down in two shootings last month . Two of the victims , including a pregnant woman , were U.S. citizens living in El Paso , Texas . CNN 's Esprit Smith contributed to this report .
NEW : There may be drug dealers retaliating several recent arrests , police say . Six police officers , one civilian killed Friday in noon shootout in Ciudad Juarez , Mexico . Five of the dead were federal police officers , one was a female city officer , police says . Six officers , one civilian wounded .