Authorities say a suspect who chanted pro-Palestine slogans was in custody.

The two were shot and killed as they left an event at the Capital Jewish Museum, about 2 km from the White House.

Washington Metropolitan Police Chief, Pamela Smith said a man shot at a group of four people with a handgun, hitting both the victims. He was seen pacing outside the museum prior to the shooting.

The victims, Yaron Lischinsky and Sarah Lynn Milgrim, were locally employed staff, the Israeli Foreign Ministry said. They were trying to promote reconciliation between Israelis and Palestinians, separate advocacy groups each belonged to said.

Smith said the single suspect, identified as 30-year-old Elias Rodriguez from Chicago, chanted "Free Palestine, Free Palestine", after being taken into custody by event security having entered the museum.

"Once in handcuffs, the suspect identified where he discarded the weapon, and that weapon has been recovered, and he implied that he committed the offense," she said, adding that he had had no previous contact with police.

Witness Katie Kalisher, 29, said she was among people in the museum who were chatting to a man who entered looking very scared after gunshots were heard outside when he suddenly pulled out a keffiyeh scarf.

"He says, 'I did it. I did it for Gaza, free, free Palestine'. And he's chanting this. And then suddenly the police come in and they arrest him,” said Kalisher, a Jewelry Designer.

--Reuters--