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A 19-year-old man with no apparent criminal history was arrested for allegedly killing three people and wounding a fourth in a series of random, unprovoked shootings in Detroit on Sunday, police said during a news conference Monday.
The suspect, whose name has not been released, was arrested roughly 12 hours after allegedly committing the last shooting when someone close to him recognized him in a surveillance photo police officials released during a search for him and contacted authorities, officials said.
"Yesterday, I made a plea to family and friends of the shooter to turn him in. It didn't seem likely that he could be taken into custody without incident," Detroit Mayor Mike Duggan said during Monday's news conference. "But, in fact, somebody close to him did respond. It was that community input that allowed the police officers to take this individual into custody without any further violence."
Police Chief James White said investigators are probing the suspect's movements prior to his arrests to determine if he targeted anyone else.
"I will tell you that it's a 19-year-old and we don't see any criminal history at this time, and we have some indication that there is mental illness," White said.
The random shootings all occurred on the west side of Detroit in the span of 2 hours and 25 minutes Sunday morning.
The sole survivor of the rampage, an 80-year-old man, described being shot while out walking his dog.
An all-hands-on-deck search involving multiple law enforcement agencies -- including the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and the Department of Homeland Security -- took place Sunday afternoon after police determined the same gun was used in all four shootings, authorities said. While ATF did not respond physically to the scene, ABC News was told the agency is assisting with an urgent trace on the weapons and working on analyzing the shell casings.
White said a 9mm handgun was recovered from a residence where the assailant was arrested. He said ballistic tests done immediately on the firearm confirmed suspicions from shell casings collected at each crime scene that it was used in all of the shootings.
When asked whether detectives have determined a motive for the rampage, White said, "Obviously, there is nothing that should motivate you to do something this tragic."
Commander Michael McGinnis of the Detroit Police Department laid out a timeline of the shootings, saying the first occurred at 4:45 a.m. when a 28-year-old man was approached by the suspect and shot.
McGinnis said the shooting was unprovoked and that the suspect walked away briefly before returning and shooting the victim several more times, killing him.
McGinnis noted that no one called 911 to report the first shooting, a detail both White and Duggan said they found troubling.
"I know from the time I spent with the officers yesterday, they're going to be haunted for a long time. They very likely could have prevented two and probably three tragedies had they had an immediate notice," Duggan said.
Detroit does not have a ShotSpotter gunfire detection system like many large cities, which immediately notifies police of the location of gunshots, Duggan and White said.
White added, "What we don't want to happen is gunshots to become commonplace in our community. We don't want to become desensitized to someone shooting in our community. There should never be a condition ever that someone uses a gun in our community that's unaccounted for."
McGinnis said the second shooting happened 30 minutes after the first shooting. In that episode, a 911 caller reported that a woman in her 40s was lying on a sidewalk with multiple gunshot wounds. He said the victim was found three blocks from the first shooting.
The victim, who died at the scene, has yet to be identified, McGinnis said.
McGinnis said that as officers were investigating the second shooting, they responded to the sound of gunshots nearby and found another woman fatally shot. He said the woman had been waiting for a bus when the suspect walked by her, returned and shot her without provocation.
He said the suspect walked away, but returned and shot the woman again.
At 7:10 a.m., an 80-year-old man out walking his dog was confronted by the suspect, who allegedly shot him and his dog in yet another unprovoked attack. The victim suffered a bullet wound to the leg, and neighbors who heard the gunshots likely saved the man's life by coming to his aid and putting a tourniquet on his leg and getting him to a hospital immediately, McGinnis said.
The names of the victims were not immediately released.
White said the suspect did not rob or attempt to rob any of the victims.
White said technology played a key role in cracking the case, explaining that it allowed investigators to quickly analyze shell casings from each of the crime scenes and determine that the same gun was used in all four shootings.
"If someone uses a weapon in our community, we're going to use every resource we have to lock you up and we make no apologies about that," White said. "Enough is enough. This is unacceptable and it needs to stop."
ABC News' Alex Stone contributed to this report.