Protesters savagely beat district security guards, at times bashing bloodied men lying incapacitated on the ground, as an opposition-aligned demonstration against the ongoing blockade of freedom park erupted into violence on Tuesday morning.

At least eight district security guards were injured - some severely - while three Cambodia National Rescue Party lawmakers-elect were taken into custody.

The protest, which formed near the edge of the park at Naga Bridge, kicked off when two groups, one led by Cambodia National Rescue Party lawmaker elect Mu Sochua, joined forces, then unfurled a banner reading “Free the Freedom Park” and attached it to the razor wire barricade surrounding the park.

Things proceeded peacefully for several minutes before a group of 30 to 40 baton wielding Daun Penh district security guards arrived and began pulling down the banner while forcefully attempting to disperse the demonstration.

Protesters, many wearing yellow ribbons, reacted immediately, rushing toward the guards, engaging them physically and quickly gaining the upper hand.

Police stationed behind the razor wire fired what appeared to be tear-gas canisters, which only briefly halted the scene unfolding outside the barricades.

In the ensuing chaos, Post reporters witnessed numerous guards being isolated and beaten by the crowd. In a moment captured by a Post video journalist, a guard is seen lying unconscious on the ground, before having a rock smashed against his head. When an ambulance arrived, protesters blocked it from reaching the scene and turned it away.

In the aftermath, rights group Adhoc said that eight guards had been injured, with four of them injured seriously. A number are now being attended to in hospital.

"Our NGOs are very sorry about this. Because of the culture of violence, previously security officials beat demonstrators and now the demonstrators beat the security in revenge," Ath Sam Ath, a technical adviser from the rights group Licadho said.

"Now our NGOs are calling for the political parties stop using the people as the tool for protecting their powerful [members]," he added

Sochua, along with fellow CNRP lawmakers elect Kaeo Phirom and Men Sothavarin, were detained by police during the melee and escorted behind the razor-wire barricades. They have since been taken to Phnom Penh municipal police headquarters, Sochua told a Post reporter via phone.

Military Police spokesman Kheng Tito said the detaining of Sochua and her fellow lawmakers-elect was simply procedure.

“Generally, after an incident like this, our authorities must detain the leaders of a violent strike to question as procedure,” he said.