Decatur police are investigating how a shooting victim arrived at Decatur Morgan Hospital Friday afternoon.

Police say officers responded to the hospital in reference to a man who arrived suffering from an apparent gunshot wound.

The man was transported to Huntsville Hospital, where he remains in critical condition.

The incident touched off security measures with Decatur City Schools. According to the school system, Decatur High and Decatur Middle were in a security perimeter in reference to “a shooting in the parking deck of Decatur-Morgan Hospital.” By 2:31 p.m., the perimeter had been lifted at both schools.

Detectives with the department’s criminal investigation division are continuing to investigate.

Police believe the shooting is an isolated incident.