Luigi Mangione Seen as He Arrives Under Tight Security at Court, Video

Luigi Mangione arrived at a Pennsylvania court under heavy security Thursday morning for his extradition hearing -- and video briefly captured the Ivy League grad surrounded by police.

Check it out ... An Altoona, PA, police car initially drives past a scrum of photogs outside the courthouse and parks inside an open garage.

Police officers then help Mangione -- wearing an orange jumpsuit with hands cuffed behind him -- out of the backseat, escorting him inside the building. From the camera's vantage point, you can only catch a glimpse of the serious look on Luigi's face.

Protestors both for and against Luigi held signs outside the courthouse ... some calling him the obvious villain ... while others demonized the insurance industry.

As you know ... Mangione is expected to waive extradition at today's hearing so he can be sent back to NYC to face state charges of murder and other offenses in connection with the fatal shooting of UnitedHealthcare CEO Brian Thompson in NYC.

This week, Manhattan D.A. Alvin Bragg announced Mangione's indictment, saying some of the murder charges are considered an act of terrorism.

Mangione is also reportedly facing federal criminal charges related to the Thompson slaying, but that indictment remains sealed for now.