Chicago police captured alleged iPhone thieves with the help of the Guardian Angels and some technology.

A woman says four teens stole her iPhone at the Chicago Red Line stop just after 12:30 a.m. Tuesday.

The phone has a tracking app, and police and the Guardian Angels followed it to the CTA's Brown Line station at Chicago and Franklin.

A Guardian Angel says the thieves got on the train, which took off before police could arrive.

"The train proceeded four more stops where several police officers were able to apprehend two of the individuals at the LaSalle and Van Buren stop on the way down with the iPhone in their possession," a Guardian Angel said.

Those two suspects are charged with strong-arm robbery of a CTA passenger, which is a felony.