Bangkok, Thailand (CNN) -- Thai security forces fired on crowds of anti-government protesters just outside the capital, Bangkok, Wednesday as tensions flared in the latest round of confrontations between the two groups.
"This is a very tense and intense standoff," CNN's Arwa Damon reported. "There is row upon row of riot police."
Live ammunition and rubber bullets were being used by security forces, according to Damon.
The Erawan rescue agency said eight protesters were injured in the clashes. One soldier was accidentally killed by fire from security forces, police said.
Riot police and government troops had massed along a major highway to stop the progress of an anti-government convoy headed toward a location where demonstrators have gathered in the past.
Security forces and riot police were trying to disperse protesters, while the demonstrators along other portions of the highway stood in the way of troop reinforcements.
Rainfall cooled the conflict for a time, stopping the advance of riot police and government troops.
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Under government rules of engagement that have been published, troops are allowed to used tear gas on demonstrators that come with 100 meters (just over 100 yards), and live ammunition on those that come within 30 meters (about 100 feet).
Thousands of anti-government protesters have brought Thailand's capital to a standstill as they seek to unseat Prime Minister Abhisit Vejjajiva's government, which they say is illegitimate and undemocratic -- accusations that Abhisit on Monday called "unfounded."
The demonstrators -- known as "Red Shirts" because of their clothing -- support Thaksin Shinawatra, who was prime minister from 2001 to 2006, before he was ousted in a bloodless coup.
More than two dozen civilians and military personnel have died since protesters began occupying key tourism and shopping areas in Thailand's capital.
Explainer: What are the protests in Thailand about?
The latest fighting came as the British Foreign Office warned British citizens against traveling to Thailand unless absolutely necessary, citing the ongoing political unrest there.
"This advice reflects our concern that violence could break out during the increasingly volatile political crisis," the Foreign Office said in a message posted on its website Wednesday.
Last week, the U.S. State Department issued a similar advisory for Americans.
Protesters in Thailand clashed today with government police, killing at least one soldier and wounding eighteen more in what media reported as being a "very tense and intense standoff."

The violence, unusually outside of the center of Bangkok, included Thai security forces firing on protesters, apparently with both rubber bullets and live ammunition, which police had been authorized to use in self-defense. The conflict took place along a highway that a convoy of protesters was travelling along; government forces were trying to disperse the demonstrators.

Casualties of the fighting included one dead — a soldier apparently killed by friendly fire — and at least eighteen injured, including eight demonstrators.  Government forces had, according to reports, fired both into the air and into the protestors from behind defenses such as razor wire and concrete pilings in an attempt to disperse the crowd.

The demonstrators have largely paralyzed the city of Bangkok for the past seven weeks in protests that have killed at least 26 people.  Largely rural and urban poor, they say they will not leave until the Thai prime minister, Abhisit Vejjajiva, resigns and new elections are held; many support former PM Thaksin Shinawatra, and consider they were deprived of their votes when he was ousted in a coup in 2006.  The fighting has led to constant rumors of a military crackdown on the city.