The announcement Friday by Marion County Sheriff Frank Anderson came on the day when two more men died.
A police officer found a man dead inside a car Friday afternoon just two blocks from the scene of a deadly shooting outside an under-21 club last week. Police did not immediately release details about the death, but called it an apparent homicide.
One of the victims of the Aug. 5 nightclub shootings, Billy Isaac Jr., 18, died Friday from his wounds. Jack Berry, 16, who was also shot, died that day. A 19-year-old man was being held without bail in the shootings.
Mayor Bart Peterson has declared the crime spree an "extreme emergency" and called for an extra $54 million increase in public safety and criminal justice spending in 2007.
Cab drivers have been the targets of several robberies during the recent crime wave, the sheriff said. One cabbie was shot and killed on Aug. 2 in what detectives believe was a robbery.
Anderson said officers, some uniformed and others in plain clothes, will patrol in cabs and also pick up customers.
"These good citizens that are driving these cabs, they are not going to be prey, easy prey for people who intend to do wrong," Anderson said.
Even before the rash of killings stunned the city of about 863,000, Indiana's capital already was on track for its bloodiest year since 1998, when 162 people died. So far this year, 95 people have been slain.
Police have stepped up patrols in trouble spots and lengthened officers' shifts.