After the official announcement of the King's death from the Bureau of the Royal Household at around 7pm, the outpouring of grief at the hospital began, with many learning of his passing on social media. They shouted: "Long live the King".
All day yesterday at the hospital, people sat on the ground around a monument of His Majesty the King's father and wept. Some passed out. Nurses performed first aid.
"Please don't leave us," screamed a tearful Pornprapa Srisang, a 43- year-old businesswoman, who arrived at the hospital late yesterday afternoon. "Please wake up and stay with your people. You just sleep, I know. You are so tired and you just fall asleep. Please stay with us."
Waraporn Sertsurin, a 28-year-old corporate employee from Bangkok, had refused to believe the rumour that the King was dead, which spread until about 7pm.
After composing themselves, people sang royal songs expressing their best wishes for the King before shouting relentlessly: "May the King go to heaven".
The singing continued for almost half-an-hour before fading as the crowds descended into a quiet period of mourning.
Some tried to edge closer to the hospital, while others thought they saw a curtain close in a hospital room. It could not be confirmed it was the room where the King had been treated.
At 9pm, some people began to leave the hospital grounds, while others stayed and continued to sing the royal songs and shout: "Long live the King".
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Nationwide, millions of people simultaneously were grief stricken. Several residents in the far Western Tak province, who were praying with monks in temples, burst into tears after learning the news.
In Chiang Mai, people had followed reports on the King's health in major venues including the busy markets via TV, before falling into silence upon learning of his death. The old city went quieter than usual.
Ubon Ratchathani resident Supit Phongsri was shocked by the news, and struggled to accept it.
"I feel today is the saddest day in my life, but I do wish he rests in peace and goes to heaven," Supit said.
A retired Royal Irrigation Department chief who worked for His Majesty, Pramote Maiklad, said he felt very lucky to have had the chance to serve him closely.
Pramote said that in the King he saw genius, which he wholeheartedly embraced as a guide for his own life.
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"His Majesty the King was very knowledgeable and masterful," he said. "He was also extremely patient, not giving things up easily. And more importantly, he worked well with others for the best outcomes."
Rattana Vejjanchai, a civil official, wished that the news of the King's death was not true but she would continue to follow in his footsteps - working for the people without thinking of herself.
State agencies including the Secretariate of the House of Representatives, praised His Majesty the King as a champion of democracy.
The Office of the Prime Minister issued an instruction to government officials nationwide to wear black to mourn the King for one year and fly flags at half mast for 30 days.