NEW : A first and final suspect has turned himself in , police say . Student government , religious groups plan prayer vigils for students . one students killed , Two wounded Tuesday several hours , officials say . Shooting prompted lockdown at University of Central Arkansas in Conway .
NEW : A fourth and final suspect has turned himself in , police say . Student government , religious groups plan prayer vigils for students . Two students killed , one wounded Sunday night , officials say . Shooting prompted lockdown at University of Central Arkansas in Conway .