(CNN)The men came after 2 a.m. on Tuesday in the dead of the night, banging on an apartment door in a rundown housing complex in Shanghai. When nobody answered, they pried open the lock and barged in, rousing a 92-year-old woman from her bed.

The visitors demanded to take the woman and her 74-year-old son to a quarantine center, because, according to their records, both had tested positive for Covid-19 five days earlier on April 14. When the old woman refused to go -- both she and her son had since tested negative -- she was allegedly pulled out of bed and dragged onto the floor. Fearing the worst, her son helped her dress and agreed to comply.

The account of events, as told in a series of online posts by the woman's granddaughter Zhi Ye, a former journalist born and raised in Shanghai, has sparked shock and fury across Chinese social media.

"There's no limit to the cold-blooded cruelty and violence," said the top comment under Zhi's post on Weibo, China's Twitter-like service.

Amid public outcry, the local government issued a statement on Tuesday evening, confirming the late-night transfer of the two elderly residents to a quarantine site. It said police and neighborhood committee workers had a locksmith pry open an outer door to the apartment because they feared "an accident had happened" to its occupants.

The statement said the two elderly residents had agreed to the transfer after communicating with police officers and "voluntarily went downstairs" to get in the car.