The driver of a semi-truck was killed Thursday evening in an overturn crash on the transition road from the westbound 60 Freeway to the 605 Freeway in Whittier, authorities said. The single-vehicle incident was reported shortly before 11 p.m. and prompted the California Highway Patrol to issue a Sigalert. The unidentified driver was pronounced dead at the scene. The collision was caused by speeding, according to CHP investigators. All lanes were expected to remain closed on the transition road until at least 8 a.m. Friday, as Caltrans crews worked on repairing a damaged guardrail. DEVELOPING: More details will be added to this report as they become available.