Heartbreaking details have emerged on a young couple shot and killed in an “antisemitic” attack outside a Jewish museum in Washington.

The man and woman — who worked for the Israeli Embassy — were “about to be engaged,” said Israel’s ambassador to the US Yechiel Leiter.

“The young man purchased a ring this week with the intention of proposing to his girlfriend next week in Jerusalem.

“They were a beautiful couple who came to enjoy an evening in Washington’s cultural centre.”

The suspect, identified as 30-year-old Elias Rodriguez, was yelling “free, free Palestine” after he was arrested, police said.

The couple was leaving an event at the Capital Jewish Museum when the suspect approached a group of four people and opened fire, Metropolitan Police Chief Pamela Smith said at a news conference.

The suspect was seen pacing outside the museum before the shooting, walked into the museum after the shooting and was detained by event security, Smith said.

When he was taken into custody, the man began chanting, “free, free Palestine”, Smith said.

Attorney General Pam Bondi said she was at the scene with former judge Jeanine Pirro, who serves as the US attorney in Washington.

Danny Danon, Israel’s ambassador to the United Nations, called the shooting, which took place on Wednesday night US time, a “depraved act of anti-Semitic terrorism”.

“We are confident that the US authorities will take strong action against those responsible for this criminal act,” Danon said in a post on social media platform X.

“Israel will continue to act resolutely to protect its citizens and representatives — everywhere in the world.”

-with AAP