WASHINGTON >> The man accused of fatally shooting two staff members of the Israeli Embassy in Washington outside a Jewish museum told police after his arrest, “I did it for Palestine, I did it for Gaza,” federal authorities said Thursday in announcing charges in the killings they called a targeted act of terrorism.

Elias Rodriguez, 31, shouted “Free Palestine” as he was led away after his arrest, according to charging documents that provided chilling new details of the Wednesday night attack in the nation’s capital that killed an American woman and Israeli man who had just left an event at the museum. They were set to become engaged.

The stunning attack prompted Israeli missions to beef up their security and lower their flags to half-staff. It came as Israel pursues another major offensive in the Gaza Strip in the war with Hamas that has heightened tensions across the Middle East and internationally, and that law enforcement officials have repeatedly warned could inspire violence in the U.S.

Rodriguez faces charges including murder of foreign officials and did not enter a plea during a perfunctory court appearance. Additional charges are likely, prosecutors said, as authorities continue to investigate the killings as both a hate crime against the Jewish community and terrorism.

“Violence against anyone based on their religion is an act of cowardice. It is not an act of a hero,” said Jeanine Pirro, interim U.S. attorney for the District of Columbia. “Antisemitism will not be tolerated, especially in the nation’s capital.”

The two people killed were identified as Yaron Lischinsky, an Israeli citizen, and Sarah Milgrim, an American. They were a young couple about to be engaged, according to Yechiel Leiter, the Israeli ambassador to the U.S. Friends, colleagues and former professors paid tribute to the pair Thursday as having dedicated themselves to promoting peace and aspiring to bridge cultural and religious divides.

“Sarah and Yaron were stolen from us,” said Ted Deutch, chief executive of the American Jewish Committee, which organized the event. “Moments before they were murdered, they were smiling, laughing and enjoying an event with colleagues and friends. We are in shock and heartbroken as we attempt to process this immense tragedy.”

An FBI affidavit made public Thursday presents the killing as calculated and planned, with authorities alleging that Rodriguez flew to the Washington region from Chicago on Tuesday with a handgun in his checked luggage. He purchased a ticket for the event about three hours before it started, the affidavit said.