Station 36 was dispatched around 20:50 for a MVA with fire at the Route 28 South bound off ramp following a Police Pursuit on 28SB. E36 went enroute within a few minutes of dispatch followed by R36 about a minute later. Before arriving on scene dispatch updated incoming Fire/Ems units that there were three patients with serious injures. Fire/Ems units started patient care and and shut down all southbound lanes of the interchange. Units from Freeport, Saxonburg, Citizens, Eureka and AK Pulser we on scene. They transported all patients to PGH hospitals. The southbound Exit ramp was closed for approximately 4 hours for PSP investigation. The SB entrance ramp was opened after about an hour and a half after dispatch. units cleared at about 1:10. Units on scene were E-36, R-36, B-36, E-27, TKR-27, B-27, FP-27, EMS 70, 45, 110, 281, Pulser, Multiple PSP units from Kittaning and Butler, Buffalo Twp PD.