President Obama says Americans were heartbroken by the loss of 193 Dutch citizens aboard Malaysian Airlines Flight 17, which was shot down by pro-Russia separatists in Ukraine on Thursday.

The president visited the Embassy of the Netherlands in Washington on Tuesday, en route to a West Coast fundraising trip, to sign a condolence book honoring those killed in the attack.

“Obviously we are all heartbroken,” the president said in a message to the Dutch people. The president expressed America’s solidarity with the Netherlands, promising “to make sure that loved ones are recovered, that a proper investigation is conducted and that ultimately justice is done.”

Peter Mollema, the embassy’s deputy chief of mission, praised the “an outpouring [of support] from the American people” and added he was “deeply grateful.”

The president arrived at the embassy just after 11:15 a.m. He spoke with Mollema outside the embassy for several moments, the Dutch flag flying at half staff above them. Inside, the president somberly processed through a silent entrance hall, signing his name to a condolence book placed on a small table adorned with white linen.

Obama is en route to the West Coast for a fundraising swing that will bring him through Seattle, San Francisco and Los Angeles.