Otto Warmbier, the 22-year-old student who was returned in an unconscious state last week from North Korea, died Monday, his family said.

"Surrounded by his loving family, Otto died today at 2:20 p.m.," his parents, Fred and Cindy Warmbier, said in a statement.

Otto Warmbier's doctors at University of Cincinnati Medical Center said last week that he had extensive brain damage dating back longer than a year. They said he was in a state of unresponsive wakefulness and wasn't aware of his surroundings.

The doctors who treated Warmbier said they had agreed not to speak about his outlook, but they had said he did not require help breathing.

The Warmbier family did not say how Otto died.

"We would like to thank the wonderful professionals at the University of Cincinnati Medical Center who did everything they could for Otto. Unfortunately, the awful torturous mistreatment our son received at the hands of the North Koreans ensured that no other outcome was possible beyond the sad one we experienced today," the family said in their statement.

Related: Three Americans Still Held by North Korea

"It would be easy at a moment like this to focus on all that we lost — future time that won't be spent with a warm, engaging, brilliant young man whose curiosity and enthusiasm for life knew no bounds," the family added.

"You can tell from the outpouring of emotion from the communities that he touched — Wyoming, Ohio and the University of Virginia to name just two — that the love for Otto went well beyond his immediate family."

Warmbier, a student at the University of Virginia, was detained in Pyongyang in January 2016 while on a tourist trip to North Korea. He was charged with committing a hostile act against the government after officials said he had tried to steal a propaganda banner from a hotel. After a one-hour trial, he was convicted and sentenced to 15 years' hard labor.

Warmbier's father, Fred, said his son was "brutalized" by the North Koreans.

Related: Otto Warmbier's Strange, Sad Trip

In their statement, the family said that "when Otto returned to Cincinnati late on June 13th he was unable to speak, unable to see and unable to react to verbal commands."

"He looked very uncomfortable — almost anguished. Although we would never hear his voice again, within a day the countenance of his face changed — he was at peace," they said. "He was home and we believe he could sense that."

Young Pioneer Tours, the Chinese travel agency that organized the 2015 trip to North Korea that included Warmbier, told NBC News on Monday night that it would no longer offer North Korean tours to U.S. citizens, saying, "The assessment of risk for Americans visiting North Korea has become too high."

In an emailed statement, the company called Warmbier's detention and treatment "appalling."

"Despite constant requests, we were denied any opportunity to meet him or anyone in contact with him in Pyongyang, only receiving assurances that he was fine," it said. "There has still been almost no information disclosed about his period in detention."

Politicians condemned North Korea.

"Melania and I offer our deepest condolences to the family of Otto Warmbier on his untimely passing," President Donald Trump said in a statement. "There is nothing more tragic for a parent than to lose a child in the prime of life.

"Otto's fate deepens my Administration's determination to prevent such tragedies from befalling innocent people at the hands of regimes that do not respect the rule of law or basic human decency," the president said. "The United States once again condemns the brutality of the North Korean regime as we mourn its latest victim."

Sen. John McCain, R-Arizona, a member of the Homeland Security and Armed Services committees, said Warmbier was "murdered by the Kim Jong-un regime."

"The United States of America cannot and should not tolerate the murder of its citizens by hostile powers," McCain said in a statement issued through his Washington office.

Secretary of State Rex Tillerson also had condolences for the Warmbier family.

"We hold North Korea accountable for Otto Warmbier's unjust imprisonment, and demand the release of three other Americans who have been illegally detained," Tillerson said in a statement.