WASHINGTON - An American journalist kidnapped and held hostage for about two years by an al-Qaida-linked group in Syria was released Sunday less than a week after the horrific execution of American journalist James Foley by Islamic militants.

The freed American is Peter Theo Curtis of Massachusetts. He wrote under the byline Theo Padnos, officials and family members said.

White House national security adviser Susan Rice said Curtis is now safe outside of Syria. Secretary of State John Kerry said Curtis was held by an al-Qaida-linked militant group fighting the government of Syrian President Bashar Assad.

A senior administration official said Curtis was released in the Golan Heights, where he was met by US government personnel who were transporting him to Tel Aviv. The official was not authorized to speak by name and discussed the release on the condition of anonymity.

"My heart is full at the extraordinary, dedicated, incredible people, too many to name individually, who have become my friends and have tirelessly helped us over these many months,'' Curtis' mother, Nancy Curtis, said in a statement from the family. "Please know that we will be eternally grateful.''

"He seems to be in good health,'' Curtis' cousin Viva Hardigg said in an interview. "We are deeply relieved and grateful for his return and the many people who have helped up secure his freedom. At the same time, we are thinking constantly of the other hostages who are still held and those working to help them be freed. We want to do everything we can to support their efforts.''

Kerry, a former senator from Massachusetts, voiced relief and gratitude for Curtis' release, "particularly after a week marked by unspeakable tragedy.''

"Theo's mother, whom we've known from Massachusetts and with whom we've worked during this horrific period, simply refused to give up and has worked indefatigably to keep hope alive that this day could be a reality,'' Kerry said.

The news comes days after the Islamic State group posted a web video showing the murder of James Foley, an American journalist who was kidnapped in 2012 while covering the Syrian uprising. The group said the killing was in retaliation for US airstrikes in northern Iraq.

The Islamic State and the al-Qaida linked group that had held Curtis have split and parted ways. US officials say the Islamic State is the far more ruthless organization.