As you probably remember, the first group was arrested by al-Nusra Front.

Via Middle East Eye:

Opposition fighters in Syria have reportedly arrested a fresh group of US-trained rebel fighters shortly after they entered the country from Turkey, The Times in London said.

According to the reports, 75 US-trained fighters entered into Syria from Turkey over the weekend in the US’s latest attempt to construct a “moderate” opposition force within the country.

“Seventy-five new fighters trained in a camp near the Turkish capital entered Aleppo province between Friday night [18 September] and Saturday morning, [19 September],” Rami Abdel Rahman, director of the Syrian Observatory for Human Rights, told AFP on Sunday.

However, on Monday the Times reported that the US-trained fighters had been arrested by the Shamiya Front (also known as the Levant Front) a Saudi Arabia, Qatar and Turkey-backed coalition of mostly Islamist rebel groups.