<p>A bicyclist was critically injured when a semi hit him Friday morning on the Southwest Side, marking at least the fourth hit-and-run crash this week, two of which have been fatal.</p><p>Around 6:50 a.m., the 37-year-old bicyclist was riding north in the 6400 block of South Kedzie Avenue when he tried to turn left and was struck by a semi-truck going south on Kedzie Avenue, Chicago police said.</p><p>The cyclist suffered a head injury and he was taken to Advocate Christ Medical Center in Oak Lawn where he was in critical condition, police said. </p><p>The truck driver did not stop. </p><p>Friday morning's hit-and-run is at least the third such incident to happen citywide this week.