Two people were wounded in a shootout Saturday night inside an Old Town business on the North Side.

Just before midnight, a 26-year-old man was inside a business in the 1600 block of North Wells Street when a man he knew entered and pulled a firearm out after an argument, Chicago police said.

The 26-year-old man also pulled out a gun and both opened fire, police said. He suffered a graze wound to the chest and refused medical attention.

The other man, described in his late 20s, was shot in the chest, head and abdomen, officials said.

He went to Northwestern Memorial Hospital, where he was in critical condition, police said.

Area detectives were investigating.