Authorities were called at about 9:30 p.m. Saturday to the 4800-block of North Milwaukee Avenue. The 7-Eleven is on the north side of a strip mall.
Shortly before 1 a.m. Sunday, SWAT members were still on the scene.
Police did not disclose details about what led to the standoff or who was involved.
CTA Blue Line trains were not stopping at the Jefferson Park station due to the police activity, according to a CTA tweet at about midnight.
Blue Line trains continue to not stop at Jefferson Park station due to police activity. Shuttle bus service is available.— cta (@cta) September 11, 2016