On 1/20/99, Ann Arbor Twp Fire was dispacthed to US-23 south of Earhart for PIA with extrication. Rescue 12-2 and Engine 12-8 arrival to find jack-knifed semi and one car with one entraped "yellow" pt. While on scene, another PIA with extrication occured approx .5 mile from scene also on US23. All AATFD resources were still committed, thus Ann Arbor City Fire was called for a mutual aid response. Rescue 1 and Engine 5 handled from AAFD.