Victoria Police have so far arrested 33 people for various offences at today's protests, including: assault police, obstruct police, hinder police, assault, arson and blocking roadways.
A Victoria Police spokesperson said protesters threw damaging missiles at officers during scuffles, and sprayed police with acidic substances.
"This morning, those police have been pelted with missiles including bottles filled with liquid, rocks, and horse manure whilst trying to protect the attendees of the Land Forces expo, some of whom were also assaulted by protestors," a spokeperson said.
"Some police have been spat at by protestors, whilst other officers have been sprayed with a liquid irritant, some of which has been identified as acid."
"Twenty-four police officers, from Victoria and interstate, have required medical treatment so far."
Victoria Police also said a number of police horses are believed to have been targeted by some protestors, who have thrown missiles at them.
However, no injuries to any of the horses have yet been recorded.
In response, Victoria Police said they deployed a range of crowd-control tools.
"Officers have been forced to deploy various tactical options, including foam baton rounds, flash distraction devices, and PAVA powder (PAVA is a synthetic Oleoresin Capsicum product) to respond to those committing offences and to deter further offending," a spokesperson said.