How do you know confrontations between the public and the police have gotten out of hand?

When the public starts building catapults, slingshots, trebuchets, using bow and arrows and crafting creative barricades out of anything they can, you have a pretty good indication.

Here are a few of the contraptions Hong Kong protesters have turned to, as tensions escalate.

RELATED: HONG KONG POLICE HAVE AI FACIAL RECOGNITION SOFTWARE

"This is war"

The Hong Kong protests, which started in response to a proposed amendment of an extradition bill that would allow Hong Kong citizens to be more easily sent to mainland China, have rapidly escalated over the past few months. Leading protesters have been cited as saying "this is a war."

In August it was reported that Hong Kong police were ordering "Robocop-style" armor for the protests. They have also banned laser pointers and turned to water cannons and other means to disperse civilians.

In response, Hong Kong citizens have become creative.

Flaming slingshots and wooden catapults

As one commenter on the Reddit post describing this DIY flaming slingshot puts it: "note to self, do not f*ck with engineers."

The protesters, described in the Reddit post as engineering students from the Chinese University of Hong Kong (CUHK), attached a hard helmet to elastic tied to what looks like bamboo.

The contraption shown above isn't the only way Hong Kong protesters are harking back to medieval wartime engineering.

Other CUHK protesters assembled a catapult on the number 2 bridge of the university's campus.

Classes are currently canceled at the university due to the protests, giving students like these enough time to focus on building weapons for the protests.

Getting creative with barricades

One of the most effective methods for law enforcement to disperse a crowd is via water cannons. The incredibly powerful streams of water they shoot out are practically impossible for a person withstand.

To fight this, protesters have turned to creative methods for barricading streets and impeding passage for police vehicles.

The barricade shown below is made of bricks, bamboo and what looks like zip ties, used to keep the barricade together.

A vehicle would have real trouble getting through such a structure. Trying to would likely result in the bamboo snapping and damaging moving parts.

For such a simple device it is likely extremely effective, as it could destroy the underside of a vehicle that drove over it.

Other protesters have strewn bricks around streets to impede vehicles — as shown above — and bricks have also been used to build walls and create lines of defense against police forces.

How to deal with tear gas?

Hong Kong protesters are even turning to creative methods for dealing with tear gas. As the citizen below shows, a simple thermos flask can be used to quickly extinguish tear gas.

Some posters speculate the thermos might contain sand, water or salt, while others claim it might be airtight. If the latter is the case, oxygen within the tight space would be quickly consumed meaning the burning would stop and the tear gas would be extinguished.

What do you do when the tear gas has already spread? A leaf blower might come in handy.

Flaming arrows and "weapons factories"

As the protests get increasingly violent, there have been reports of students raiding sports departments for bows and other equipment that could be used as weapons.

There have been no reports of flaming arrows causing any injuries thus far, and commenters argue that they are being used mainly as part of an intimidation tactic by protesters.

As per Reuters, reports have emerged that CUHK has been turned into a "weapons factory." Protesters, on the other hand, claim that police instigated the violence and turned the university campus "into a warzone," forcing them to defend themselves.

In an age where modern technologies — namely social media — are being used by protesters, it's interesting to see some turning to building contraptions resembling medieval war machines.

It is a sign of a desperate situation that shows no signs of dying down any time soon.