CNN  —  A network of hospitals in East Texas has not been able to accept ambulances to emergency rooms since Thanksgiving Day because of a “potential [cyber]security incident,” a hospital spokesperson told CNN on Friday. The hospital network, UT Health East Texas, is operating using “established downtime procedures” as the hospital investigates “a potential security incident” and works to bring computers back online, spokesperson Allison Pollan said in an email. Pollan did not respond to subsequent phone calls seeking more information on the incident and how the hospitals were…