Derrik Sweeney, 19, Gregory Porter, 19, and Luke Gates, 21, were detained over the weekend.
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Derrik Sweeney's mother, Joy, told CNN she was "so blessed and so grateful" at the news of the release, which was confirmed by a spokesperson for the Egyptian prosecutor's office.
The three had been told they could return to their dorm rooms, after undergoing a medical examination and completing some paperwork, Joy Sweeney said.
She indicated the US consul general in Egypt, Roberto Powers, had advised that the students leave the country for their own safety, since their faces have become widely known via local media.
Luke Gates' father, Bill, told Fox News he had booked a flight for his son to return to the US Friday.
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Prosecutors say the students were found with a bag containing empty bottles and gasoline, but the trio insist the bag belonged to their Egyptian classmates, according to prosecutor's office spokesman Adil Saeed.
State television showed them lined up against a wall, holding bottles filled with a yellow liquid.
Sweeney told his mother they had been treated "relatively well" during their detention, she informed the AP.
All three students were on a study-abroad program at the American University in Cairo.
The US Embassy in Cairo is advising all US citizens to avoid Tahrir Square and the surrounding area, saying it has received reports of "foreigners detained for photographing security forces and unfolding events in Cairo and other cities."
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