Karmelo Anthony‘s family was slated to address the teen’s murder charge at a news conference roughly an hour ago — but they put a pause on the proceedings … as the father of the boy who Anthony allegedly killed unexpectedly showed up to the event.

The tense scene just unfolded minutes ago at Next Generation Action Network’s headquarters in Dallas … when Austin Metcalf‘s father, Jeff Metcalf, surprisingly appeared among media members just minutes before the Anthonys were about to speak.

Reportedly, NGAN officials did not want to have the Metcalfs and Anthonys in the same room — and asked Jeff to leave.

Seconds ago, a cop was seen speaking with Jeff … and he left.

The Anthonys had vowed to “clear the record” at the newser regarding claims that had been made about Karmelo following allegations he stabbed Austin during a dispute at a high school track meet earlier this month.