Complex sentence: On 23 March 2007, three people were killed when three trucks and four cars collided in the tunnel, resulting in a fire and forcing the evacuation of motorists from both the Burnley and Domain tunnels.
Split into simpler sentences: On 23 March 2007, three people were killed in an accident involving three trucks and four cars. The accident resulted in a fire and forced the evacuation of motorists from both the Burnley and Domain tunnels.