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Two American-born soldiers for the Israeli Defense Forces were killed in fighting in the Gaza Strip, their families confirmed Sunday.

Stuart Steinberg confirmed the death of his son Max Steinberg, 24, to The Associated Press on Sunday. Steinberg, whose family lives in Southern California's San Fernando Valley, was a sharpshooter for the Golani Brigade. He was one of 13 Israeli soldiers killed in fighting Sunday during the first major ground battle in two weeks of fighting between Israel and Hamas.

Earlier Sunday, the IDF said in a statement that Sgt. Nissim Sean Carmeli, 21, was killed in combat in the Gaza Strip. Carmeli was from South Padre Island, Texas, said Deputy Consul General of Israel to the Southwest Maya Kadosh. She said Carmeli moved to Israel four years ago and added that the consulate helped his family get a flight there Sunday.

Late Sunday, the State Department also confirmed the soldiers' deaths, but made no further statement.

Rabbi Asher Hecht of Chabad of the Rio Grande Valley, who is a longtime family friend, said Carmeli joined the Israeli Army after finishing high school in Israel and was in the Golani Brigade. The IDF statement said Carmeli was from Ra'anana, Israel.

"He had great energy, yet had a kind and gentle soul," Hecht said. "It's been a very tough day for us," he added. "We lost a gem."

Carmeli was the youngest of three and has two sisters who currently live in Israel. He was "loved by his parents infinitely," Hecht said.

More than 18,000 people from across Israel showed up Monday for Carmeli's funeral in Haifa, police said.

Carmeli was a fan of the Maccabi Haifa soccer team, and a team member — after learning Carmeli had no family living in Israel — sent a Facebook message to fans urging them to attend the funeral.

Steinberg was living in Beersheba, Israel. He attended Pierce College and El Camino Real High School in Southern California.

He visited Israel for the first time on a Birthright Israel trip with his younger brother and sister in June 2012, his father said. When he returned, he made an announcement to his parents that he was planning to return and join the IDF, Steinberg said. He made good on that promise less than six months later, making the move in December.

"He went back," Steinberg said. "He was completely dedicated and committed to serving the country of Israel. He was focused, he was clear in what the mission was, and he was dedicated to the work he needed to be doing."

The Times of Israel reported that seven of the 13 soldiers killed before dawn Sunday died when an anti-tank mine exploded under an armored personnel carrier. Hours later, the paper reported that two more soldiers were killed in an exchange of gunfire with Hamas militants, and three others died when an anti-tank missile struck a building where soldiers were setting up a command post.

Sunday morning's fighting took place in the Shijaiyah neighborhood in the northeastern part of Gaza City. Israel has identified the area as a primary launch site for rockets fired by Hamas targeting Israel territory.

On Sunday morning, the Steinbergs were visited by representatives from the Consulate General of Israel in Los Angeles. They broke the news of Max Steinberg's death.

Stuart Steinberg last spoke to his son at 4 a.m. Saturday California time, hours before his death. Max Steinberg called his father to tell him that his group had been injured when two of their tanks collided. They had to return to Israel for treatment at the hospital. Some soldiers had broken bones, and Max Steinberg had sprained his back, his father said.

"He called me up at 4 a.m. that morning and said he'd be returning to Gaza, back to combat, to be with his friends," Steinberg said.

Steinberg said the family is leaving on Monday for Israel, where their son will be buried. On Max Steinberg's Facebook page, hundreds of people liked a profile photo that appeared to be a selfie of him in uniform, armed, with his helmet on. Dozens gave their condolences.

Jay Sanderson, who heads The Jewish Federation of Greater Los Angeles, said in an email message to the community that "our thoughts are with his family and our community is committed to support them in any way they need -- and to honor Max's memory."

The Jewish Federations of North America said in a statement that its "deepest sympathies" were with the families of 18 Israeli soldiers killed over the last two days. "Along with all of Israel, and the entire Jewish People, we mourn their loss as if they were our own," the statement said.

IDF Chief of Staff Gen. Benny Gantz told The Times of Israel that the IDF "would learn from the incident" and said that its soldiers were doing "fantastic work."

"I'm proud of them," Gantz told the paper. "All of Israel should be proud of them."

Click for more from The Times of Israel.

The Associated Press contributed to this report.