Bethel Park police said Darrick Dauberger, of Pittsburgh, stole thousands of dollars in pain medication from a pharmacy on Sunday.
Witnesses said Dauberger's arrest at an apartment building on Carson Street was a full tactical operation by police.
"They had fully automatic machine guns and other pistols on their hips. They had bulletproof vests on and other body armor as well," said Steve Yeager, who works nearby.
Yeager said Dauberger didn't surrender to police right away, but eventually surrendered.
"There were undercover guys, big vans and armored vehicles. They had it all locked down. They had him pulled out sitting in the back in handcuffs," Yeager said.
The owners of Spartan Pharmacy said Dauberger's arrested brings them relief.
"I know the employees that were there, and myself as a business owner, and the other owner feel very safe. This was taken care of so promptly and we don't have to worry each day something else may happen," said Kevin McCaffrey.
McCaffrey said he credits Bethel Park police and witnesses that helped identify Daugberger for his fast arrest. McCaffrey said he hopes it sends a strong message to any other would-be robbers.
"I hope people will think twice before doing something like this," McCaffrey said.
Dauberger is in the Allegheny County Jail facing robbery and several other charges.