PHILADELPHIA — Two Pennsylvania State Police troopers and a civilian were killed in a car crash on I-95 early Monday, in what law enforcement officials described as a possible DUI incident. Colleagues and friends remembered the fallen officers as devoted public servants and young community leaders whose promising careers were cut short by a tragic incident, with unanswered questions as the investigation continued into Monday evening. The troopers responded to calls about a man walking in a southbound traffic lane near Lincoln Financial Field around 12:45 a.m. Monday. As they tried to bring the…