cnn's scott lane is there. >> we know very little about what happened, but we are learning bits and pieces. we know that a lot of residents in this condo complex, there are 15 to 20 buildings in this area and they are two-story walk ups. this is a pretty sleepy corner of suburban denver. for many people it wasn't clear what it was. one person said it sounded like firecrackers and another said it sounded like heavy construction that had been going on nearby. as we know now, it was gunfire. one woman who lived there told me she believed that the shooting lasted between 30 seconds and one empminute and i sounded like there was an exchange meaning multiple weapons being fired and what