Gunfire rang out across a busy intersection in Thailand's capital for more than an hour today as government supporters clashed with protesters trying to derail tense nationwide elections one day before the vote begins.
At least seven people were wounded, including an American photojournalist.
People caught up in the mayhem crouched behind cars and ducked on a pedestrian bridge while others fled inside a nearby shopping centre.
Several masked gunmen wearing armoured vests bent down under a highway overpass as one of them fired a weapon concealed in a green sack.
The exchange of fire was the latest flare-up in a months-long struggle by protesters to overthrow prime minister Yingluck Shinawatra's beleaguered government, which they accuse of corruption.
The turmoil raises the prospect of more violence tomorrow, when polls open for an electoral contest that has devolved into a battle of wills between the government and protesters - and those caught in between who insist on their right to vote.
The latest confrontation began after a group of pro-government supporters marched to a district office in the northern Bangkok suburb of Laksi. The office had been surrounded by protesters intent on preventing ballot boxes housed inside from being delivered to a nearby polling station tomorrow.
Tensions mounted for hours before clashes finally broke out. As gunfire rattled the area and people screamed in fear, an enraged mob of pro-government supporters wielding huge sticks smashed the windshields of a car carrying protesters that sped away.
Journalists saw a gunman allied with protesters firing an assault rifle, and another firing a pistol as he lay on his stomach on the road. Sunai Phasuk, a senior researcher for Human Rights Watch, said several pro-government gunmen climbed to the centre's rooftop and began firing down toward rivals. The two sides also fought with rocks and firecrackers.
According to the city's emergency services, at least six Thais were wounded, including a reporter for the local Daily News newspaper. An American photojournalist, James Nachtwey, was grazed by a bullet in the leg.
The conflict pits demonstrators who say they want to suspend the country's fragile democracy to institute anti-corruption reforms against Ms Yingluck's supporters and civilians who know the election will do little to solve the nation's crisis but insist the right to vote should not be taken away.
The protesters, a minority that cannot win power at the polls, are demanding the government be replaced by an unelected council that would rewrite political and electoral laws to combat deep-seated problems of corruption and money politics. Ms Yingluck has refused to step down, arguing she is open to reform and such a council would be unconstitutional.
Since protests began late last year, at least 10 people have been killed and nearly 600 wounded.
"How did we get to this point?" asked Chanida Pakdeebanchasak, a 28-year-old Bangkok resident who was determined to cast her ballot tomorrow no matter what happens. "Since when does going to vote mean you don't love the country?"
Although unrest already hit Bangkok and polling stations may not open in some parts of the south if ballot materials don't arrive in time, voting is expected to proceed smoothly in most of the country.
Police said they will deploy 100,000 officers nationwide, while the army is putting 5,000 soldiers in Bangkok to boost security. More than 47 million people are registered to vote.