Two Russian doctors who have treated coronavirus patients died in falls from hospital windows and a third was seriously injured in the last two weeks.

Police are continuing to investigate the circumstances of the incidents, but early reports indicated two of the doctors had protested working conditions during the pandemic while the third had been blamed for her colleagues contracting the virus, The Associated Press reported.

Alexander Shulepov, a doctor who works on a Voronezh ambulance crew south of Moscow, fell from the second-floor window May 2 while hospitalized with coronavirus, the AP reported. He broke several ribs and fractured his skull in the fall. The fall occurred shortly after his colleague, Alexander Kosyakin, posted a video of Shulepov saying he had been forced to finish his shift after testing positive for the virus.

Shulepov later retracted his complaints in a separate video posted by local health officials, and Kosyakin is reportedly under investigation on suspicion of spreading false news about personal protective equipment shortages.

The circumstances of Shulepovs fall are unclear, with some local media reports suggesting he was attempting to climb out the window to smoke a cigarette while others have claimed it was a result of pressure after voicing his complaints.

Meanwhile, Yelena Nepomnyashchaya, acting head of a hospital in the western Siberian city of Krasnoyarsk, died May 1 after falling from a fifth-floor window on April 25. She reportedly fell shortly after arguing against converting a ward for coronavirus patients, saying there was insufficient PPE, but was unable to convince local health officials. City officials have denied such a call occurred.

The third doctor, Natalya Levedeva, fell out of a Moscow hospitals window on April 24 after she was admitted with suspected coronavirus, dying immediately. Officials have said Levedevas death was an accident but local reports suggested she had become distraught over accusations that she had failed to protect her staff from infection.

Russia has reported 166,000 cases of the virus and 1,537 deaths, but the government has not made any official data available on the number of health care workers who have died from it, according to the AP.