More Americans remain “unaccounted for” and the government is working with Israeli officials to learn more about their wellbeing and whereabouts, Biden said in a statement.

Biden said many of the American citizens that were killed had “made a second home in Israel” and described their deaths as “heart wrenching.”

Additionally, the White House believes it is likely American citizens are among the scores of civilians that Hamas has taken hostage, but it is still working to confirm.

Biden said he spoke with Israeli Prime Minister Benjamin Netanyahu Sunday and told him that the U.S. “will continue to make sure Israel has what it needs to defend itself and its people.”

Biden also said that he’s ordered his team to assist Israeli officials in this crisis including by sharing intelligence and deploying government experts.