Renault Laguna turbo or injection?

car flashed up fuel injection fault on display, then engine raced and my husband was unable to slow it down or stop car! he tried cutting engine, stalling it but nothing worked . he had 2 overtake 3 cars to aviod hitting them. when he de -clutched car was surrounded in smoke and he thought it may have caught fire. he said he just kept jumpin on the pedals and eventually it stopped car, he pulled over and revs died down. mechanic is sayin its turbo gone bit worried it may have caused engine damage or may do it again . any ideas or suggestions?