Chicago police said two persons of interest are in custody in connection with the shooting of a preschooler on the city's Southwest Side Wednesday evening.

According to police, the child, a 4-year-old boy, was traveling in a minivan driven by a 23-year-old man in the 3100 block of South Ashland Avenue, near the diagonal Archer Avenue, just after 7 p.m.

That's when another vehicle pulled up behind the van, and someone from inside pulled out a gun and shot at the van, hitting the boy in the back. The minivan driver was not injured.

The family took the boy to the University of Illinois Medical Center before he was transferred to Stroger Hospital, where he remains in critical but stable condition at last check.

The shooting left the southbound stretch of Ashland closed for hours for investigation.

Surveillance video led police to take two persons of interest into custody. 

The motive behind the shooting is still unclear, including whether the gunman knew the family inside the van, or whether they knew or cared that a child was present.

Police released no further information on the persons of interest in custody, including if or when charges will be filed. 

In:
• Child Shot
• Shooting
• Southwest Side

Asal Rezaei contributed to this report.