Left workers erupted in protest in Siliguri in North Bengal and even at Barasat near Kolkata as senior leaders condemned the "attack".
"Drama," scoffed Mamata Banerjee's tourism minister, and promptly sent two Trinamool councillors to hospital too, with "chest pain".
Trouble began during a board meeting in the civic body. Trinamool councillors reportedly demanded an allocation of Rs 10 lakh for each civic ward for "cultural activities".
Mr Bhattacharya reportedly scoffed at the "culture" that the Trinamool had spawned in Bengal.
Immediately, papers and bottles of water went flying. Among them a bag apparently hit the mayor.
Mr Bhattacharya was rushed to his room and then wheeled into hospital with what his party leaders said was a head injury.
Soon after, two Trinamool councillors were also wheeled into the ICU with chest pain. Trinamool leaders said they had been injured in the free for all at the mayor's meeting.