(Salem, OR)  --  Police are investigating two separate incidents in Salem, in which victims were robbed while trying to sell items they had advertised online.  Authorities say the robberies happened late Saturday night and early yesterday morning in the same parking lot on Lancaster Drive Northeast.  Police say in both incidents, the victims were robbed at gunpoint, and shots were fired during the second robbery.  No one was injured.  Authorities say witnesses described the suspects as Hispanic men in their 20s, about five-feet-seven inches tall, who ran from the scene with the stolen items.