One of the first doctors who flagged the new coronavirus outbreak in the city of Wuhan, China has died.

His death triggered a wave of grief and anger among Chinese social media users, many of whom were already frustrated with the government's handling of an outbreak that has killed hundreds and infected thousands in China. Some who were more critical of the government included the hashtag #IWantFreedomOfSpeech in their posts, but that hashtag was censored on Weibo.

Ophthalmologist Li Wenliang sounded the alarm in December when he told a group of doctors on Chinese social media about seven cases he saw. He and seven other whistleblowers were reprimanded by the Wuhan police in January for spreading "illegal and false" information.

Li was later infected with the coronavirus himself after treating patients with the virus.

He died at 2:58 a.m. local time, the Wuhan Central Hospital announced on China's Twitter-like service Weibo. He was 34.

Chinese social media had already been buzzing with anger and concern about Li's health for several hours. From late Thursday night, state-run media were already reporting that he had died, before the hospital said he was still in critical condition.

@globaltimesnews: Update: Li Wenliang is currently in critical condition. His heart reportedly stopped beating at around 21:30. He was then given treatment with ECMO(extra-corporeal membrane oxygenation).

The World Health Organization also expressed its condolences, although it said it did not have information on Li's status as of 2:35 a.m.

@WHO: At today's #2019nCoV media briefing @DrMikeRyan was asked about reports that Dr Li Wenliang had passed away, and he expressed condolences. WHO has no information on the status of Dr Li.

The social media outpouring was immense and soon morphed into greater frustration with the establishment and its handling of the coronavirus outbreak which has spread globally.

On Friday morning, the two most popular hashtags on Weibo were related to Li's death. China's ubiquitous messaging app WeChat was filled with condolences.

The comments ranged from respect and sadness over the loss of a "hero." Some referenced lyrics from Les Miserables' "Do You Hear the People Sing." Others repeated a quote from Li to Caixin Media, "A healthy society should not only have one voice."