A prominent Chinese doctor who tried to warn fellow doctors about the deadly coronavirus has died, the hospital treating him confirmed.

Dr. Li Wenliang died after he contracted the virus from a single coronavirus patient he treated in a Wuhan hospital. He was 34.

Wuhan Central Hospital, where Li was treated in ICU, confirmed his death on Friday, Feb. 7, after initially denying reports that he died on Thursday.

On Dec. 30, Li sent a chat group message to fellow doctors warning them about seven patients who had been quarantined in a Wuhan hospital with a mysterious illness that resembled SARS (severe acute respiratory syndrome).

Within hours, the message went viral on social media, and Li was summoned to the Public Security Bureau, the BBC News reported.

“When I saw [the message] circulating online, I realized that it was out of my control and I would probably be punished,” Li told CNN from his hospital bed in Wuhan.

The police demanded Li sign a document denying his claims about a new virus. Meanwhile, thousands of people contracted the illness and hundreds died before Chinese officials announced the epidemic on Jan. 8.

The Chinese government is accused of suppressing the true scale of the epidemic. The death toll has doubled in just 24 hours to 630 with over 28,000 infections worldwide. But critics say the true numbers are probably much higher.

There are 12 confirmed coronavirus cases so far in the United States.