At least four people are dead, and 24 others were injured in separate shootings across Chicago over the past weekend, police said. On Dec. 11, a man who was identified as 26-year-old Siraj Mahadeva was shot and killed while standing on the porch of a friend’s house on the Northwest Side, officials told the Chicago Sun-Times. The man was found by his friend after the friend heard a loud sound at around 3:25 a.m., authorities said. Mahadeva was taken to Mount Sinai Hospital, where he was pronounced dead, officials said. Another man was fatally shot around noon in the West Pullman neighborhood of the Far South Side on Dec. 11, authorities told news outlets. Ralph Williams, 38, was sitting in a vehicle near West 119th Street when two individuals approached the car before one opened fire, officials said. Williams, who was hit in the back, was taken to Christ Medical Center in Oak …