(KRON) — A Berkeley native is among the Americans who are missing following one of the bloodiest weekends in Israeli and Palestinian history. The family of 23-year-old Hersh Goldberg-Polin said he was likely taken hostage by Hamas militants.

Goldberg-Polin was at an Israeli music festival close to the Gaza border when Hamas terrorists attacked, killed 260 young adults, and kidnapped hostages Saturday morning, the Jewish Telegraphic Agency reported.

Goldberg-Polin sent his father two WhatsApps messages Saturday morning. The first message said, “I love you.” In the second message he wrote, “I’m sorry,” according to JTA.

Goldberg-Polin moved with his parents from the San Francisco Bay Area to Israel when he was 7 years old.

Thousands of young men and women had gathered at a vast field Saturday in southern Israel to dance at the outdoor electronic music festival. Rockets and gunshots erupted, taking the crowd by surprise. The New York Times published harrowing video showing festival-goers running for their lives.

“We were hiding and running, hiding and running, in an open field — the worst place you could possibly be in that situation,” survivor Arik Nani told the Associated Press. Nani had gone to the festival to celebrate his 26th birthday.

Hersh Goldberg-Polin’s mother, Rachel Goldberg, and father, Jonathan Polin, attend a news conference on Oct. 10, 2023 in Tel Aviv, Israel. (AP Photo / Maya Alleruzzo)

Goldberg-Polin had just completed his mandatory army service earlier this year, JTA reported. An unknown number of people from the festival were taken hostage. On Tuesday, Goldberg-Polin’s mother said her son is believed to be among the hostages.

The mother, Rachel Goldberg, spoke to reporters at a press conference held in Israel on Tuesday. She was one of six American-Israeli dual citizens who pleaded for the U.S. and Israeli governments to secure the hostages’ release.

Rachel Goldberg said some festival-goers fled with her son and found a bomb shelter. Hamas terrorists found the group Saturday morning, threw hand grenades into the shelter, and used machines guns to shoot inside, The Hill reported.

According to eyewitnesses, Goldberg-Polin’s arm was blown off and he made his own tourniquet using his shirt, The Hill reported.

“They were all civilians at a music festival. They were fish in a barrel sitting in this bomb shelter,” Rachel Goldberg said.

Jack Tews told KRON4 that Goldberg-Polin is his cousin. Tews told KRON4, “Hersh was last known to have made it to a bomb shelter near the festival with a few survivors. Hamas militants threw grenades into the bunker which he and another young man threw back. Eventually the Hamas militants broke the door to the shelter down with machine guns and fired on survivors inside. To my knowledge his phone let off a ping in or very near to Gaza.”

Goldberg-Polin was reportedly taken hostage because he was still able to walk Now his parents are holding out hope that their son is alive.

The White House is lit up blue and white on Oct. 9, 2023 as a symbol of the United States’ solidarity with the people of Israel in the wake of the horrific terrorist attacks committed by Hamas. (Photo courtesy The White House)

Berkeley Mayor Jesse Arreguin wrote on X Tuesday, “The senseless and horrific attacks by Hamas extremists on Israel have shocked Berkeley and the world. Now we have learned of two people with ties to our city who have been affected. We send our prayers to the families of Hersh Goldberg-Polin … and Rabbi Yonatan Cohen.”

At least 11 U.S. citizens have been confirmed dead in the Hamas attacks, U.S. President Joe Biden said. Biden also said the U.S. government believes it is “likely” that Americans are among those currently being held hostage by Hamas militants, while other U.S. citizens are still unaccounted for after the deadly assault.

Hamas warned on Monday that it will kill an Israeli hostage every time Israel’s military bombs civilian targets in the Gaza Strip without warning.

The Associated Press contributed to this report.