Family members, friends and thousands of mourners bade farewell Thursday to Otto Warmbier, the American college student who died shortly after his release from North Korea in a coma.

The funeral service was held at Warmbier's alma mater, Wyoming High School. The front of the funeral program included a quote from Warmbier's 2013 graduation speech: "This is our season finale. This is the end of one great show, but just the beginning to hundreds of new spinoffs."

Local media said about 2,500 people well-wishers lined up outside the school's arts center to pay respects to Warmbier. The service was conducted by a rabbi and lasted about one hour. Blue and white ribbons (the school's colors) adorned trees around the school to honor Warmbier.

In attendance was Amb. Joseph Yun, the US special representative for North Korea policy, who visited Pyongyang and brought Warmbier home. Yun conveyed a condolence message from South Korean President Moon Jae-in to Warmbier's family.

Others included Sen. Rob Portman (R-OH) and Deputy Secretary of State John Sullivan.

Portman was quoted as telling reporters that Warmbier was an "amazing young man" and North Korea must be held accountable for his death.

Warmbier, a 22-year-old University of Virginia student, died Monday, six days after he returned to his Ohio home in a coma after

17 months of detention in the North for taking down a political propaganda sign from a hotel.

North Korean officials claimed Warmbier fell into a coma in March last year due to botulism and a sleeping pill. Doctors in the US said Warmbier had severe brain damage and was in a state of "unresponsive wakefulness."

His family blamed the "awful torturous mistreatment our son received at the hands of the North Koreans."

US President Donald Trump has condemned the "brutality" of the North Korean regime and Secretary of State Rex Tillerson vowed to hold Pyongyang accountable for the death. (Yonhap)