Relatives of U.S. citizens feared to have been taken hostage by Hamas urged the Biden administration Tuesday to help free their loved ones, saying they had yet to receive “formal communication” from the White House.

Rachel Goldberg, the mother of Hersh Goldberg-Polin, 23, said at a news conference here that the last words she received from her son came in a message telling her he loved her and that he was “sorry.”

Goldberg-Polin was among thousands of revelers when Hamas terrorists descended on a music festival Saturday, leaving at least 260 people dead and taking an unknown number of attendees hostage.

Goldberg said she heard from witnesses that part of her son’s arm was “blown off” before he was taken by the militants, who ordered anyone who could to “stand up and walk.”