(CNN) -

After almost two years in captivity, Peter Theo Curtis is finally home.

The American released Sunday after being held in Syria briefly addressed a gaggle of reporters in Cambridge, Massachusetts, on Wednesday.

"I had no idea when I was in prison so much effort was being expended on my behalf," he said, explaining that he was grateful for those who tried to secure his release from Islamist militants.

"Total strangers have been coming up to me (saying), 'Hey, we're just glad you're home,' said Curtis, who was dressed in jeans, sandals and a T-shirt.

"I suddenly remember how good the American people are and what kindness they have in their hearts," he added. "I'm overwhelmed by emotion."

The 45-year-old professional writer thanked journalists for expressing such great interest in him, but he said he had to bond with his mother and he just couldn't bring himself to give an interview now. "That's all I can say to you," he said, promising to give interviews later and "help you guys do your job."

"I will respond," he said, "but I can't do it now."

He then stepped away from the cameras.

An end to a traumatic ordeal

Curtis flew Tuesday from Tel Aviv, Israel, to the United States, stopping in Newark, New Jersey, before reuniting with his mother in Boston, his family said earlier in a news release.

"I have been so touched and moved, beyond all words, by the people who have come up to me today -- strangers on the airplane, the flight attendants and, most of all, my family to say welcome home," Curtis said.

Curtis' mother Nancy, said she was "overwhelmed with relief" that he had returned.

But given the recent death of American journalist James Foley, who was beheaded by militants with ISIS, she couldn't bring herself to celebrate.

Curtis was believed to have been captured in October 2012 and held by al-Nusra Front, a rebel group with ties to al-Qaida. Al-Nusra is a different rebel group than ISIS.

"I don't think anybody's in the mood of celebration. You know, we're relieved," Nancy Curtis earlier told CNN outside her home in Cambridge, Massachusetts. "But after the events of the last week and knowing those other children of my friends are in danger, you know, I have very conflicted emotions. I've come to know the other families as well, and these kids have a lot in common."

Matt Wormser, a Vermont resident and Peter Theo Curtis' former high school roommate, said it was a "very bittersweet time" for friends and relatives of the freed hostage.

"It's been tremendously difficult for Nancy," he said.

The first person Nancy Curtis contacted after confirming that her son had been released was Foley's mother, Diane, she told "ABC World News Tonight."

"You learn to get over the panic," Nancy Curtis told CNN's Anderson Cooper. "You learn to just take each hour as it comes."

Handing over a prisoner

The United Nations said Peter Theo Curtis was handed over Sunday to U.N. peacekeepers in the Golan Heights, which is under Israeli government control, and was given a medical checkup.

State Department spokeswoman Marie Harf said Peter Theo Curtis was brought to Tel Aviv, for medical evaluations.

Harf said he appeared to be in good health.

Peter Theo Curtis made a brief call to his mother Sunday, Nancy Curtis said.

"He said, 'Mom, they're just being so nice to me. They put me in this wonderful hotel, and I'm drinking a beer, and there are women out there,' " she recalled. "Because he's been in a cellar for two years, and he hasn't seen anything, no street life or obviously no women to be seen, and so he was really excited, and he was thrilled to be in Tel Aviv and frustrated that he can't go out because the place apparently is surrounded by paparazzi."