It happened after 9:00 a.m. Wednesday.
Witnesses said the suspect walked into the business in the 6600 block of Castor Avenue and pulled out a shotgun shortly after 9 a.m.
He took cash from several customers and ran away.
Officers in the area spotted the suspect a short time later and chased him on foot.
They caught up with him in the 1200 block of Magee Street and took him into custody.
No one was injured.