CAMBRIDGE Mass. — A U.S. writer freed this week after being held captive for two years by Syrian insurgents on Wednesday thanked those who had worked for his release and said he was emotionally overwhelmed by his welcome home.

Peter Theo Curtis, who was held by Nusra Front, al Qaeda’s official wing in Syria, said he had no idea that while he was imprisoned there had been hundreds of people around the world pushing for his release.

In a written statement released overnight, Curtis also thanked the government of Qatar and U.S. officials for working to free him.

“I am just overwhelmed with emotion,” Curtis, 45, told reporters outside his mother’s home Wednesday morning.

Curtis, who was freed on Sunday, said numerous strangers had approached him to welcome him back to the United States.

“I suddenly remember how good the American people are and what kindness they have in their hearts. And to all those people I say a huge ‘thank you’ from my heart, from the bottom of my heart,” he said.

Curtis arrived in the United States late on Tuesday after a flight from Tel Aviv, meeting his mother at Boston’s Logan Airport.

His release comes against the backdrop of other efforts to free other U.S. hostages in Syria as the United States considers possible options, including airstrikes, to target the Islamic State organization.

Earlier on Tuesday, his parents said in various television interviews that they were relieved. Their son’s return came just days after rivals of Nusra Front, the militant group “Islamic State,” last week said it killed journalist James Foley and threatened another still being held hostage, Steven Sotloff.

Curtis’ ex-girlfriend, Jennifer Steil, said he spoke Arabic fluently and understood the Quran, rare attributes among Westerners who traveled to the region.

Matt Schrier, an American photojournalist held captive with Curtis, told CBS’ “60 Minutes” program in 2013 that they were tortured. Their captors suspected Curtis was an agent for the Central Intelligence Agency, possibly because he spoke Arabic well, he said.

Schrier escaped after more than six months in captivity. CBS on Tuesday said it initially withheld Curtis’ name and details of his imprisonment when it aired the segment last year to protect him.