A pro-Palestinian terrorist gunned down a couple who were set to be engaged during a devastating attack outside the Capital Jewish Museum in Washington D.C.

Israeli embassy staffer Yaron Lischinsky and his girlfriend Sarah Milgrim were named as the tragic victims of the vile attack early on Thursday morning, which was condemned by President Donald Trump.

The suspect, identified as 30-year-old Elias Rodriguez, repeatedly shouted 'Free Palestine' as he was hauled into custody, shortly after opening fire.

Lischinsky was a German-Israeli dual national employed as a research assistant for Middle East & North African Affairs at the Embassy's Political Department, according to his LinkedIn profile.

The couple had attended a Young Diplomats event at the Capital Jewish Museum.