Authorities say gunmen have killed six people at a park in the besieged border city of Ciudad Juarez, according to AP. Chihuahua state prosecutors' spokesman Carlos Gonzalez says the gunmen arrived at the park in the Francisco I. Madero neighborhood and opened fire Sunday afternoon. He says four people were wounded and are in critical condition. Gonzalez said Monday that police have not yet identified the perpetrators or a motive, but they found 180 bullet casings from the sort of assault weapons typically used by drug gangs. The park was inaugurated four months ago as part of a government program to reduce violence and boost the quality of life.