APOPKA, Fla. -

An iPhone with a GPS helped Orlando police arrest a 17-year-old suspected of carjacking a woman and her elderly passenger who had just left an Orange County church.

The teen was arrested late Wednesday night an at Apopka Walmart, about 10 miles from the church.

According to Orlando police, the woman left a church in south Orlando and was helping an elderly woman get out of her car on Deerbrock Drive when the teen jumped into the vehicle and drove off.  Neither woman was injured.

Daisy Williams, a friend of the woman whose car was stolen, witnessed the robbery. "I ran out to try to assist her and help her," Williams said, "but before I could grab the door and pull it open, he had done already hit the gas."

Police learned about the cellphone in the car and and tracked it to the Walmart near Hiawassee Road and U.S. 441.  The teen was inside shopping but was arrested when he exited the store and went to the stolen car.

"You know, we don't never know what's going to be the outcome of things that like," Williams said, "but you see somebody in trouble, you try to help them."

It's not known if the teen will be charged as an adult.

No other details have been released.

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