Deborah Matias, an American citizen who lived in Israel, was shot and killed by Hamas gunmen while shielding her teenage son from their bullets, her father told CNN.

Hayim Katsman, an Israeli-American academic, had been hiding in a closet with his neighbor when he was fatally shot, his sibling said.

They are among at least 11 US citizens who were killed in Israel after the Gaza-based militant group launched a devastating attack early Saturday that has left at least 900 people there dead.