Chaotic confrontations broke out in several locations, mostly involving pushing and shoving by the two sides, though some protesters wielded sticks and threw rocks, while security forces fired tear gas and rubber bullets. Reporters said live rounds were also fired, and a reporter for Thai TV station TPBS showed a spent bullet and bullet holes in the side of a car.
The so-called Red Shirt protesters are demanding that Prime Minister Abhisit Vejjajiva dissolve Parliament and call new elections. They claim that he came to power illegitimately in December 2008 with the help of military pressure on Parliament.
Government forces have confronted the protesters before but pulled back rather than risk bloodshed.
On Friday, the army failed to prevent demonstrators from breaking into the compound of a satellite transmission station. The humiliating rout of troops and riot police raised questions about how much control Abhisit has over the police and army.
Army spokesman Col. Sansern Kaewkamnerd told the Nation Channel cable TV station on Saturday that security forces will try to reclaim the rally site near Pan Fah bridge in the old part of Bangkok "before dusk." The area was occupied by Red Shirt protesters about a month ago. The government has issued an emergency decree and other orders making the demonstrations illegal.
He said that they would send more forces to a second rally site in the heart of Bangkok's tourist and shopping "to pressure the protesters." The city's elevated mass transit system known as the Skytrain, which runs past that site, stopped operations and closed all its stations as possible confrontation loomed.
The government's Erawan emergency center reported 93 people injured - mostly from tear gas or with bruises - including 19 soldiers and 3 police officers.
"Security forces will use proper measures to take over the public areas occupied by the protesters," government spokesman Panithan Wattanayakorn told cable TV network TNN on Saturday afternoon.
The violence has not yet approached the level of last April, when Red Shirts began rampaging on city streets and torching public buses.
On Saturday, a helicopter circled over one protest site, where protesters were trying to disable public surveillance cameras by covering them with bags or cutting their cables. At a rally site in the heart of Bangkok's shopping district, protest leaders handed out damp towels and face masks to protect against tear gas, and called for more followers to gather.
The new deployment came after protesters were pushed back by water cannons and rubber bullets from the headquarters of the 1st Army Region. Although they have two main rally sites, the Red Shirts use trucks and motorcycles to send followers all over the city on short notice.
Arrest warrants have been issued for 27 Red Shirt leaders, but none is known to have been taken into custody.
Abhisit had vowed late Friday not to bend to their demands.
(Left: A lone Buddhist monk faces off against riot police Saturday, April 10, 2010, in Bangkok.)
On Friday, protesters broke into the Thaicom transmission station and briefly restarted a pro-Red Shirt television station that had been shut down by the government under a state of emergency. After scattered hand to hand scuffles, the troops retreated in disarray, some taking positions inside the main Thaicom building. About a dozen people were hurt.
After talks were held between protest leaders and the authorities, agreement was reached to allow People Channel to resume broadcasting, and protesters and soldiers left the site. But several hours later, more than 4,000 army troops retook the transmission complex and cut off the People Channel's signal again.
Merchants say the boisterous demonstrations have cost them tens of millions of baht (millions of dollars), and luxury hotels near the site have been under virtual siege.
The escalating demonstrations are part of a long-running battle between the mostly poor and rural supporters of former Prime Minister Thaksin Shinawatra, and the ruling elite they say orchestrated the 2006 military coup that removed him from power.
They see the Oxford-educated Abhisit as a symbol of the elite and claim he took office illegitimately in December 2008 with the help of military pressure on Parliament.
"The government could be seen as humiliating itself if it fails to enforce the law," said Associate Professor Siripan Nogsuan Sawasdee, a political scientist at Bangkok's Chulalongkorn University.
To effectively enforce the state of emergency, the government needs the cooperation of the military, she said, but it could be that the army is reluctant to use force against the protesters.
Thailand's military has traditionally played a major role in politics, staging almost a score of coups since the country became a constitutional monarchy in 1932. In 2008, the army undercut the government's authority by refusing to move against demonstrators who were protesting against a pro-Thaksin government.
By Associated Press Writer Grant Peck; AP writers Denis D. Gray, Thanyarat Doksone and Ian Mader contributed to this report