China's state-run Xinhua news agency quoted a Ministry of Public Security statement saying the rumors "caused panic, misled the public and resulted in disorders in stock market or society."
The rumors in question included one that claimed a man in Beijing had jumped to his death due to the stock market slump and another that 1,300 people had died in the Tianjin explosions. Yet others included "some seditious rumors about China's upcoming commemorations of the 70th anniversary of the end of World War II," Xinhua reported.
It said 165 online accounts had been closed due to the violations.
"A journalist was also arrested along with several stock market officials, according to a Xinhua report. The journalist, Wang Xiaolu, is accused of "spreading fake information" about the market slump, the report said.
"The state news agency said Mr Wang confessed that he 'wrote fake report on Chinese stock market based on hearsay and his own subjective guesses without conducting due verifications.'"