BOSTON—A brazen robber wearing a ski mask snatched a phone from a CVS worker before sprinting down one of Boston's busiest streets — only to be caught red-handed with four bags of cocaine stuffed in his pocket.

Jason Johnson, 43, of Wenham, Massachusetts, allegedly stormed into the CVS Pharmacy at 587 Boylston Street in Boston's Back Bay neighborhood at around 10:45 PM on Monday and grabbed an employee's cellphone before fleeing into the night.

But his getaway was short-lived.

As a Boston Police officer arrived at the scene, a shaken store employee pointed frantically at the suspect, who was seen running down Boylston Street — a major thoroughfare lined with high-end shops and restaurants in one of the city's most fashionable districts.

The officer gave chase and was able to detain Johnson just moments later.

And when officers conducted a routine search of the suspect, they got more than they bargained for — discovering four plastic bags of cocaine tucked inside Johnson's pocket.

The stolen phone was promptly returned to the relieved victim.

Johnson was placed under arrest and is expected to be arraigned at Boston Municipal Court on charges of unarmed robbery and possession of a Class B drug.

The shocking incident is the latest in a string of brazen retail crimes to plague the Boylston Street corridor, where just last week police issued an alert seeking two suspects who allegedly made off with $800 worth of merchandise from the Alo yoga store.

It comes amid growing concern over retail crime in major American cities, with workers on the front lines increasingly finding themselves targeted by emboldened criminals.

Boston Police responded to 238 incidents in the 24-hour period ending Wednesday morning, including one robbery, six aggravated assaults, and six residential burglaries.