1
general::
Phrase(s): open fire (on someone)
Fig. to start (doing something, such as asking questions or criticizing). (Based on open fire on someone or something.) • The reporters opened fire on the mayor. • When the reporters opened fire, the mayor was smiling, but not for long., Phrase(s): open fire (on someone or something)
to begin shooting at someone or something. • The troops opened fire on the enemy. • The trainees opened fire on the target.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Begin a verbal attack, as in In her second letter to the editor she opened fire, saying the reporter had deliberately misquoted her. This idiom alludes to discharging a firearm. [Mid-1800s]
American Heritage Idioms