(CNN) -- Police in Flint, Michigan, are investigating 13 stabbings resulting in five deaths since late May that they believed have been committed by one man.
Race may be a factor in the crimes: A majority of the stabbing victims are African-American and the perpetrator is described by surviving victims as a white male, Flint police said.
The attacker, described by surviving victims as muscular and around 5-foot-11 to 6-foot-2, in many cases first lured his victims to his car by appearing to have car trouble or needing directions.
He then began stabbing the victims, all of whom are described as smaller men. In two cases they were people with special needs.
"He is trying to hurt people who are helping him," said Flint Police Lt. Tim Johnson.
There have also been instances when the killer walked up to his victim and began stabbing without warning. Other than descriptions by surviving victims, Johnson said, police currently have no leads.
"We are trying to get a handle on this guy. We want, No. 1, for our citizens to be safe," Johnson said.
At this point the police are stopping short of calling the murderer a serial killer.
"It's a series of events linked," Johnson said. "We think the same person is doing all of them."
The five victims who did not survive are David Motley on May 24; Emmanuel Dent on June 21; Darwin Marshall on July 26; Frank Kellybrew on July 30; and, in the most recent attack, Arnold Miner on August 2.
The crimes have occurred in all parts of Flint, not just African-American neighborhoods.
Three victims are still hospitalized.