This is a heads up to my Arizona brothers! Check out the website to see police sketches! http://www.cnn.com/2006/US/07/12/phoenix.crime/index.html?section=cnn_topstories Phoenix police are trying to solve two separate strings of killings that have terrorized the community. Authorities say they are looking for someone who has shot 34 people at random in the past year as they walked or rode bicycles, killing four. Police say the other suspect is a serial killer and rapist who has struck 20 times, killing six of his victims. Police are not saying how many of the victims were raped. (Watch what a psychiatrist thinks compels them to kill -- 3:08) "We're doing a lot of community talking right now," police Sgt. Andy Hill told CNN's "American Morning" on Wednesday. "We have a big meeting planned for the community tonight. We've been encouraging people to understand that they can be empowered if they're cautious, careful and take the time to call us with information." However, people in Phoenix say they remain on edge. "I'm afraid to walk outside," one resident said. "I'm afraid to be alone." (Watch police show how the killers operate -- 3:01) In the attacks on walkers or bicyclists, police have decided that the same person is likely responsible for a recent series of shootings and an earlier one in which four people were killed -- for a total of 34 shootings. "We believe we have enough similarities and MO to go ahead and put those two series of shootings together," Hill said. The shootings were all random, he said, and there were no witnesses. The victims all were walking alone, riding a bicycle or pushing one when the shootings occurred. "There is no connection to race or gender or sex that would indicate to us that anybody's being targeted," Hill said. The suspect is believed to have used a vehicle, possibly a light-colored sedan. But police urge anyone with information -- regardless of whether a vehicle matches that description -- to call them, Hill said. The serial killer, dubbed the "Baseline Killer," is believed to be responsible for at least 19 attacks and five homicides in Phoenix since last summer, said police Detective Stacie Derge. In the Phoenix suburb of Tempe, a sixth homicide, which happened in September, also is believed to be related, Hill said. "He started with robberies and sexual assaults," Derge said, and initially was called the "Baseline Rapist," because many of his attacks occurred near Baseline Road. The suspect has been described as a black male between 25 and 40. In some instances, he was described as bald or having a shaved head, but in others he was said to have long hair. Police suspect he may wear a wig as a disguise. CNN's Rick Sanchez contributed to this report.