WASHINGTON -- Austin Tice, a freelance American journalist who was working in Syria for McClatchy Newspapers, The Washington Post and other media outlets, has been incommunicado for more than a week, his whereabouts unknown since exchanging email with a colleague.

Tice, a Georgetown law student who previously served as an infantry officer with the U.S. Marine Corps, was one of the few foreign journalists to report from inside Syria as the civil war intensified. He entered the country in May and traveled extensively through central Syria, filing battlefield dispatches before arriving in Damascus in late July.

Tice’s reporting earned him a 2,000-strong following on Twitter, where fans of his work noted his disappearance when he stopped tweeting after Aug. 11 – when he’d recounted spending his 31st birthday listening to Taylor Swift music with rebel fighters from the Free Syrian Army.

His subsequent silence didn’t raise immediate alarm because he’d planned to leave that week, on a journey to the Lebanese border that often takes days because of the fighting en route. The Damascus suburb where he was last known to have been has faced heavy bombardment in recent days that has made communications difficult.

Tice’s family and colleagues are concerned for his safety and are asking anyone with knowledge of his whereabouts to come forward.

"We understand Austin’s passion to report on the struggle in Syria, and are proud of the work he is doing there. We trust that he is safe, appreciate every effort being made to locate him, and look forward to hearing from him very soon,” Tice’s parents, Marc and Debra, said in a statement from Houston, his hometown.

Tice’s editors said they were working with U.S. government agencies and Syrian intermediaries to retrace his movements. Colleagues praised Tice’s work, saying his experience as a Marine gave him particular insight into the capabilities of both government and rebel forces as the uprising spiraled into a civil war.

He filed one of the first detailed accounts of a battle between government forces and the guerrillas, and also wrote a piece examining the weaknesses of Syrian military tactics. Despite his close company with the rebel forces, Tice didn’t shy away from pointing out their own apparent human rights violations, such as prisoner abuse and alleged executions. Apart from McClatchy and The Washington Post, Tice also contributed to CBS News, Al Jazeera English, the AFP news agency, and the MCT Photo Service.

He maintained a wide range of contacts via email and Skype, the Internet communications service. He reached out to Middle East experts and specialists on insurgent and jihadist movements. None has reported contact with Tice since mid-August.

Tice had entered the country through a rebel-held area and was there without a visa, as is typical of many foreign journalists covering the conflict there.

Caught between the government’s shelling and the attacks of a shadowy rebel movement, reporters face so many risks in Syria that the Committee to Protect Journalists recently named it the most dangerous place in the world to be a journalist. At least 20 media workers – 10 professional journalists and 10 Syrian “citizen journalists” – have been killed in Syria since the uprising began in March 2011, according to the committee’s tally.