BANGKOK (AP) — Thailand's government declared a strict new state of emergency for the capital on Thursday, a day after a student-led protest against the country’s traditional establishment saw an extraordinary moment in which demonstrators heckled a royal motorcade.

After the pre-dawn declaration, riot police moved in to clear out demonstrators who after a day of rallies and confrontation had gathered outside Prime Minister Prayuth Chan-ocha's office to push their demands, which include the former general's resignation, constitutional changes and reform of the monarchy.

Several top leaders of the protest movement were taken into custody, with one later declaring on his Facebook page that he had been denied access to a lawyer and was being forced onto a helicopter and taken to a city in the country's north. Police said they had made 22 arrests.

Despite a new ban against large public gatherings, thousands of people rallied again in another area of the city later Thursday. The new gathering, which appeared to have drawn more than the 8,000 people police said had attended the previous night's rally, lasted about six hours and began winding down shortly after 10 p.m.

Organizers announced they would gather again on Friday.

“It shows that no matter how many are arrested, new faces will join the protest,” Patsaravalee “Mind” Tanakitvibulpon, an engineering student and protest organizer, told the online publication The Standard.

The text of the emergency declaration said it was needed because “certain groups of perpetrators intended to instigate an untoward incident and movement in the Bangkok area by way of various methods and via different channels, including causing obstruction to the royal motorcade.”

The protest Wednesday in Bangkok's historic district, not far from glittering temples and royal palaces, was the third major gathering by student-led activists who have been pushing the boundaries of what is considered acceptable — and legal — language by publicly questioning the role of Thailand's monarchy in the nation's power structure.

Thailand's royal family has long been considered sacrosanct and a pillar of Thai identity. King Maha Vajiralongkorn and other key member of the royal family are protected by a lese majeste law that has regularly been used to silence critics who risk up to 15 years in prison if deemed to have insulted the institution.

The protest — held on the anniversary of a 1973 student-led uprising against a military dictatorship — was complicated by the presence of royalist counter protesters who had gathered both to show support for the government and to greet the royal family as they traveled to and from a religious ceremony in the area.

That led to a moment captured in photos and video that circulated widely on social media in which what appeared to be protesters gestured and shouted just meters (feet) from the royal motorcade. Such actions are unprecedented in Thailand, where those waiting for a royal motorcade regularly sit on the ground or prostrate themselves.

Some experts say a line may have been crossed.

“What seemed to be a low-boil stalemate that the Prayuth government was managing with reasonable success has now, following the incident involving the procession of the queen’s motorcade down a street in which an active protest was under way and the arrests of protest leaders, become a full-blown crisis," said Michael Montesano, coordinator of the Thailand Studies Program at the ISEAS-Yusof Isak Institute in Singapore. "Unlike even 48 hours ago, the country is in dangerous territory now.”

Government spokesman Anucha Buraphachaisri announced Thursday morning that the prime minister had ordered police to take strict action against those who obstruct a royal procession or otherwise insult the monarchy.

One change is that police said they will install checkpoints around Bangkok for security purposes.

Keeping order will be facilitated by the new emergency decree for Bangkok, which bans unauthorized gatherings of more than five people and gives authorities other powers they deem needed to prevent unrest, including detaining people temporarily without charge. It also outlaws news that distorts information or could cause a “misunderstanding.”

Thailand is already under a national state of emergency as part of its efforts to fight the coronavirus, and it was not immediately clear how the new decree was different.

Protesters gathered again in a Bangkok shopping district Thursday afternoon and into the evening. The crowd grew big enough to block a major intersection flanked by upmarket malls and a famous shrine, where they were addressed by a series of speakers denouncing the government.

Police stood by while the crowd chanted rude slogans calling for the prime minister to step down. They also chanted “Free our friends,” in reference to the arrested leaders.

“I want to fight for my future. I want to fight for my friends. I want to fight for my democracy. My country must be democracy,” said 24-year-old NGO worker Aitarnik Chitwiset.

Deputy police spokesman Col. Kissana Phathanacharoen warned earlier that calling for such a protest or attending one was against the law.

The protest movement was launched in March by university students, but quickly put on hold as Thailand was gripped by the coronavirus pandemic. It came back in July, when the threat from the virus eased, and has since grown in size.

The movement’s original core demands were new elections, changes in the constitution to make it more democratic, and an end to intimidation of activists.

The protesters charge that Prayuth, who as army commander led a 2014 coup that toppled an elected government, was returned to power unfairly in last year’s general election because laws had been changed to favor a pro-military party. The protesters say a constitution promulgated under military rule and passed in a referendum in which campaigning against it was illegal is undemocratic.

The movement took another stunning turn in August, when students at a rally aired unprecedented criticism of the monarchy and issued calls for its reform. Using direct language normally expressed in whispers if at all, the speakers criticized the king’s wealth, his influence and that he spends much of his time in Germany, not Thailand.

Conservative royalist Thais accuse the protest movement of seeking to end the monarchy, an allegation its leaders deny.

Nevertheless, analysts say the incident with the royal motorcade may harden positions.

It “is not just unprecedented but will be shocking for many,” said Kevin Hewison, professor emeritus from the University of North Carolina and veteran Thai studies scholar. “Yet it is reflective of how a new generation of protesters sees the monarchy and military-backed regime as intertwined and that political reform demands reform of the monarchy as well.”