Chicago Police confirmed Thursday night that there was a spike in iPhone robberies and thefts along Michigan Avenue and the Gold Coast.
Police say they are dispatching more officers to those areas.
Since Sunday, at least three men and one woman have been targeted for their high-tech phones.
On Thursday, a suspect was arrested in connection with one of the cases.
"Be very, very careful, especially if you have an iPhone," said the female robbery victim, a 33-year-old Chicago mother. She said she was attacked from behind on Tuesday for her iPhone.
She was walking alone on Superior near Michigan Avenue.
"I think he hit me with one hand and took my phone with the other," she said.
The robbery happened at about 6 p.m.
"It can happen in broad daylight on Michigan Avenue - the busiest street in the city of Chicago, when there's lots and lots of people around, and you can't stop the person," said the victim.
Chicago author John D. Thomas said he was attacked Monday while waiting for a bus at Michigan and Grand. He said two thieves teamed up to snatch his iPhone.
"We're taking every one of these incidents very seriously," said 42nd Ward Alderman Brendan Reilly. "I can tell you the 18th Police District, which covers downtown and the Mag Mile, have detailed additional officers, both plainclothes and bicycle patrol officers."
Overnight, police arrested and charged 22-year-old Naeem Summers with robbery, saying he snatched a man's iPhone early this morning on the 1000-block of Rush Street. He is not charged with any other crimes.
Summers was caught while running on Lake Shore Drive early Thursday morning.
The victim told police he and a friend were talking at Rush and Oak Street in the Gold Coast when Summers grabbed his iPhone and took off.
Both the victim and his friend chased the suspect down and managed to alert police.
Officers spotted him and stopped him.
Summers was taken into police custody, and the owner of the iPhone got his phone back.
Some iPhone users are aware of the crimes, including an employee at a bakery near the Apple Store where victims have dashed in for help.
"They first come in, 'Oh my God, I lost my iPhone! Somebody stole my iPhone!'" said iPhone user and witness Devon Hoy. "The only thing we can do is call the police, so kind of used to that by now."
Police advised iPhone users to be alert and aware of who is around them.
One sergeant compared it Thursday night to the era when robbers targeted people for their Air Jordans or leather coats.
Alderman Reilly said owners should treat their iPhones like a piece of jewelry and try not to be too flashy.