Police said Dey was arrested after he surrendered this morning.
A local court later remanded him to five days police custody.
Dey had gone into the hospital leading a group on Friday night brandishing the firearm to threaten its staff following a spat. The act was caught on CCTV.
Hospital authorities had said that Dey started the spat and its staff had pleaded him to return.
TMC MP Shatabdi Roy and other party leaders have denounced the act and said action should be taken against the suspended leader.