MOSCOW (Reuters) - Smoke rising from a coronavirus hospital in Moscow was caused by a loss of pressure in an oxygen tank at a building under construction and no staff or patients had been at risk, the city’s health department said on Wednesday. Witnesses told television channel NTV that a loud bang had been followed by smoke billowing from one of the buildings at the Kommunarka hospital complex, one of Moscow’s main coronavirus centres. Russia has already experienced fires at coronavirus facilities, with more than 150 patients evacuated from a temporary hospital in October following an oxygen explosion and five patients killed in May when an overloaded ventilator started a fire in an intensive care unit in St Petersburg. “There were no patients in this block. There were no casualties. The relevant services are correcting the malfunction. There is no threat to patients and hospital staff,” the Moscow health ministry said in a statement.