Pheonix ? People aren’t going out alone at night anymore. Co-workers are walking to their cars in pairs in the evenings. Parents aren’t letting their children out of their sight.

Fear and paranoia have gripped this sprawling city amid reports that not one, but two serial killers have been striking separately in recent months, killing as many as 11 people at random on the darkened streets.

“I’m terrified,” said 25-year-old Valerie Alvidrez, who lives alone with her 6-month-old daughter in the central Phoenix area where many of the killings have occurred. “It’s scary. If something happens, I have to defend me and my daughter.”

The killings and woundings of at least 16 other people evoked the terror of the 2002 Washington-area sniper shootings because of the randomness of the crimes and the fact the victims were struck down while going about their daily routines. People have been shot from behind while biking; one victim was vacuuming her car at a carwash, another was waiting for a bus.

Six of the killings are being attributed to the “Baseline Killer,” whose name refers to the street where he is believed to have committed his first crimes. Police say the man likely wears a disguise – a wig of dreadlocks topped by a fisherman’s hat – and strikes just after sunset. Five of his victims have been women. Police have not said how all his victims were killed but several were shot.

The second suspected predator, dubbed the “Serial Shooter,” has been definitively linked to the Dec. 29 wounding of one man, and authorities believe he could be responsible for a total of five shooting deaths. Police say the shooter likely watches victims – mostly pedestrians and bicyclists – and strikes from behind when no one is looking. The shootings usually occur late at night or in the early morning. Sixteen Serial Shooter victims have survived.

The number of crimes stand out, even in what is one of the nation’s most violent cities for its size. Police statistics show a homicide occurred in Phoenix, which has about 1.5 million residents, every 38 hours on average in 2005.

Police have created two task forces made up of a total of 120 officers to investigate the crimes, and officials have collected $100,000 as a reward for information leading to the arrest of either suspect.

“We know we’re always in a race against the clock,” said police spokesman Sgt. Andy Hill. “We don’t want there to be another victim.”

Police won’t disclose what specific evidence in either set of killings leads them to believe the crimes are connected, but say time of day and locations play a part.