Customers at a North Dallas fast food restaurant were shocked to hear gunfire in the parking lot late last night. It started out as an undercover drug buy but it ended with one man dead and a Plano narcotics officer answering questions. Dallas police say the plain clothes officer agreed to meet a suspect in the parking lot of a Jack in the Box on the frontage road of the Dallas North Tollway just north of Frankford.  No one’s saying why, but just before midnight gunfire erupted.  One man was gravely wounded and died early this morning at Parkland Hospital. It’s not clear whether the man had a weapon, but the the officer was not hurt. Two men at the scene were arrested, but their connection to the event is unknown. Plano police have not offered any information about why the officer opened fire.