Dozens were injured, including Payu Boonsophon, an activist who told DW he lost sight in one eye.
"When the police charged, we were resting to have lunch," said Payu. He said that at first, he was shocked because the riot police knew protesters were taking a break and did not issue a warning before charging.
"We had anticipated a dispersal, but thought the police would at most use water cannon trucks since it was a peaceful protest without weapons," he said.
On November 18, around 350 protesters, many of them rural farmers and workers, tried to march to the Queen Sirikit National Convention Center where the APEC summit was being held to denounce the government's environmental and development strategy and business-friendly policies.
"We did not expect such disproportionate use of force, as the protest focused on resource issues directly affecting people's livelihood," Patsaravalee Tanakitvibulpon, pro-democracy activist and leader of the "Citizens Stop APEC 2022" coalition, told DW.
Apart from Payu, journalists at the scene were injured, despite wearing the media armband issued by the Thai Journalists Association, said Katherine Gerson, Amnesty International's Thailand campaigner.
They were assaulted with batons and shields, and one of them was even struck in the face with a glass bottle.
Cycle of police brutality in Thailand
The crackdown was carried out despite the international attention surrounding APEC and is the latest example showing how Thai authorities use excessive force whenever demonstrators question the country's core institutions, whether it is the government, the army, the monarchy or big business.
In late 2020, during a wave of youth-led protests challenging Thailand's ruling establishment, water cannon with chemical irritants and tear gas canisters were used against unarmed demonstrators on three separate occasions.
"We documented incidents in which the Thai police unlawfully used unnecessary and disproportionate force when policing protests, including when children have been present," Gerson told DW.
One of the victims was Warit Somnoi, a 15-year-old who was seriously wounded in the neck during a rally outside the Din Daeng police station in Bangkok in August last year and later died.
Pro-democracy activist Thanat Thanakitamnuay was also permanently blinded in one eye after being shot with tear gas canisters at an anti-government rally.
"Police in Thailand have a tradition of using unrestrained force against protesters. It is when Thai police do not use force that there is a surprising exception," Paul Chambers from the Center of ASEAN Community Studies at Thailand's Naresuan University told DW.
Anja Bienert, head of Amnesty International's police and human rights program, told DW the use of rubber bullets "must only be used when less extreme means are insufficient" to contain and stop the violence, adding that "clear warnings must be given before firing."
Police also arrested 25 protesters outside the APEC summit. They were later released on bail on the condition that they refrain from taking part in any political gatherings or urging others to rally — another instrument used to restrict activists from exercising their rights.
"There needs to be real police reform and enforcement of laws which prevent police abuse," said Chambers, adding that "enforcing such reforms is a real challenge."
Demands for police reform in Thailand
Following what protesters called "bloody APEC," demonstrators are now calling for police to apologize and compensate the victims and bring those officers responsible to justice.
They are also demanding a reform of crowd control policing, calling for a disclosure of the names of officers on duty and an end to the use of rubber bullets on peaceful demonstrators.
While national police chief Damrongsak Kittiprapas has said the police would launch an investigation into the reports of injuries, Chambers doubts it will lead to any meaningful change.
"Based upon the inefficiencies of police investigations of the past, there is no reason to believe this one will be different," he said.
Payu, as well as other protesters and journalists injured, are planning to bring legal action in the hope that it will force authorities to introduce appropriate measures for crowd control.