A 78-year-old woman died in a tragic incident on southbound I-75 in Saginaw County after her SUV was struck twice by semi-trucks early Thursday morning. Michigan State Police reported that her GMC Acadia became disabled in the right lane near Dixie Highway around 6 a.m. The first collision involved a Peterbilt truck driven by a 59-year-old man from Cadillac, followed shortly after by a Freightliner truck driven by a 22-year-old from Mount Pleasant. Both truck drivers were unharmed, but the Acadia caught fire after the second impact, preventing emergency responders from rescuing the woman in time. The crash resulted in the closure of southbound I-75 for nearly three hours while the scene was investigated. The cause of the Acadia's initial stoppage is still under investigation.