A post on Sina Weibo, the Chinese equivalent of Twitter, appealed for help on Wednesday night to save scores of stray dogs trapped in a big pit near a garbage dump in Alxa Left Banner in Inner Mongolia Autonomous Region.
"Yinchuanshouhuzhedongwuzhijia" or "Home for Stray Animals in Yinchuan", a non-governmental organization (NGO), posted pictures of the dogs in the pit, including a close-up of a baby dog, state-run Xinhua news agency reported.
The photos were taken by a woman, surnamed Tan, who went to the site with five friends on Wednesday to search for a pet dog.
"We saw around a hundred dogs in a pit, but we could not get down into it because it was too deep," Tan said, adding they tried to save the dogs using ropes. They saved over 20.
She said that the dogs must have been in the hole for a long time, because they were thirsty.
A volunteer at the NGO said eight members of the agency went to rescue the dogs on Thursday, only to find the pit had been filled. Several dogs were running around, said the volunteer, without giving her name.
"The pit was five to six-metres deep. We could not dig as we didn't have proper tools," she said.
Another group said a number of dead dogs were retrieved from the pit on Friday.
Rumors on the internet said that the local Chengguan, or urban management officers, had buried the dogs alive, although the city management bureau denied such cruelty.
A member of staff with the bureau said they had caught dozens of stray dogs and put them in a rented yard because of complaints from residents that people and domestic animals had been bitten.
"We went to the yard after hearing about the reports, but only a few were there," she said.
The incident has angered many, and a post about it had been forwarded more than 18,000 times by Sunday morning.
Chinese netizens called the act "inhumane" and "shameful".
"Life is equal, how could thugs conduct such a massacre?" wrote a Weibo user with the screen name "MingyangsihaiUSA".
Stories regarding stray animals have made the headlines, causing a wave of public fury.
In May 2013, dozens of stray cats were abused and slaughtered in a residential district in Beijing, with the fur of the animals almost completely plucked out.
An activist said the government should step in and tackle the problems regarding oft-neglected stray animals.