BILLINGS, Mont. >> An American university student is free following a weeklong detention in China for allegedly injuring a taxi driver who was roughing up his mother during a fare dispute, in a case that drew objections over the student’s treatment from U.S. lawmakers.

Guthrie McLean, a student at the University of Montana, was released from a detention center in Zhengzhou early today, according to his mother, Jennifer McLean, a teacher who lives in the central Chinese city.

“We are very, very very, very happy,” Jennifer McLean wrote in an email to The Associated Press. She said the release — at 2 a.m. local time when her son was delivered to her doorstep — came as a surprise after she’d twice been told to anticipate a release only to be disappointed.

“They have not finished the process completely, but we are hopeful it will go smoothly from here on,” she said.

The U.S. State Department confirmed McClean’s release, but provided no details citing privacy concerns.

“The safety and security of U.S. citizens overseas is one of the Department’s highest priorities,” it said in an emailed statement today.

The release followed an agreement with Chinese authorities to drop any charges against Guthrie Mclean, according to Montana U.S. Sen. Steve Daines.

Further details on the agreement were not disclosed. People who answered the phones at Zhengzhou police headquarters said there was no one available to comment on the case.

Daines and U.S. Sen. Jon Tester and Rep. Greg Gianforte had pressed McLean’s case with China’s Ambassador to the U.S. Cui Tiankai and Secretary of State Rex Tillerson. The lawmakers said McLean had been justifiably defending his mother, who is deaf, from the driver, whose knee was reportedly hurt in the encounter.

Jennifer McLean told The AP the taxi driver had been pushing her around and hurting her when her son intervened and pushed the taxi driver to the ground.

Jennifer McLean said that when police detained Guthrie five weeks later on charges of intentional injury, they demanded the equivalent of $7,400 in compensation and threatened to imprison her son for up to three years if they refused to pay.

The family did not pay $7,400, according to Daines, who added that more details would be released at a later time.

“After two 20-hour days in back and forth negotiations with Chinese officials, we were able to come to an agreement that worked for everybody, most importantly for Guthrie and for Jennifer, his mother,” Daines said in a conference call with reporters.

Daines said he spoke with Guthrie McLean after his release, and he plans to return to Missoula, Montana to resume his studies next month.

Tester and Montana Rep. Greg Gianforte issued statements Sunday saying they were pleased with the outcome of the case.

Guthrie McLean has been majoring in East Asian studies at the University of Montana in Missoula for about two years and works in the Department of Modern and Classical Languages and Literatures, according to school officials.

He’s a U.S. citizen, but he largely grew up in China after living in Missoula as a young child while his mother was studying at the university, according to his boss, Olivia White.

Associated Press writer Didi Tang contributed to this report from Beijing.