Nepal's fragile peace process and the possibility of holding a key election by June received a major blow as a bloodbath in the Terai plains in the south left 27 people dead and dozens fighting for their lives in hospitals.
A violent clash on Wednesday between Maoist extremists and an ethnic Indian group from the plains spread like wildfire from border town Gaur in Rautahat district, about 160 km south of Kathmandu, to nearby villagers with warring sides pursuing each other with bamboo and wooden poles, knives and even guns.
Nepal's official media reported frequent firing as the Madhes Rastriya Mukti Morcha, the Terai unit of the Maoists, fought a pitched battle with the Madhesi Janadhikar Forum, a social organisation that became a major player in Nepal politics this year with its ongoing agitation for an autonomous Madhes state for plains people.
The violence was on the cards after the Forum and Maoists staked claim to the same area to hold a mass meeting on Wednesday.
However, with the district administration failing to take any pre-emptive measure, the two groups, who have been at loggerheads since January, began a fierce fight that claimed the lives of bystanders, including women and children.
Till late night, many of the victims had not been identified.
The Office of the UN High Commissioner for Human Rights (OHCHR) rushed a team to the simmering town to investigate the incident.
The OHCHR said that the hospital sources had indicated that some of the deaths were due to head injuries caused by beatings with bamboo batons. Dozens of other people were admitted to hospital, some with serious head injuries.
"The clashes occurred during simultaneous rallies organised by the two groups, which went ahead in spite of both organisations being aware of the potential for conflict," the OHCHR said.
Its chief in Nepal, Lena Sundh, urged the authorities to investigate the killings and hold accountable anyone found to be responsible.
The district administration on Thursday extended curfew indefinitely in the town and its neighbourhood.
Wounded people still kept pouring in at the nearby hospitals in Bharatpur and Hetauda districts, and even to Kathmandu as locals blamed the administration for failing to control the violence.
Though Nepal's ruling seven-party alliance and the Maoists expressed regret over the carnage and said that the guilty would be punished, till Wednesday night no arrests had been reported.
"Maoists have been attacking our peaceful meetings earlier too," Upendra Jha, senior leader of the Forum, said.
"They attacked our rallies in Bhairahawa, Birgunj, Nepalgunj."
"The government is deliberately setting the Maoists on us to repress the Madhes movement. But we will continue with our protests."
On Friday, the Forum has announced a civil disobedience movement in the capital when it plans to bring thousands of activists and encircle Singh Durbar, the heart of Nepal government where the prime minister's office, key ministries, parliament and other important offices are located.
The Maoists, on the other hand, said the Forum was a cover for monarchists who were trying to foment violence to sabotage the constituent assembly election scheduled for June, when Nepal's 238-year institution of monarchy would be put to vote.
"It is a lie that Maoists fired on anyone," Matrika Prasad Yadav, top leader of the Madhesi Rastriya Mukti Morcha, said.
"Had we been carrying guns, there wouldn't have been so many Maoist casualties. All the people who are dead were Maoists."
"The government is watching idly while the king's supporters are trying to create unrest under the banner of the Forum."
Prime Minister Girija Prasad Koirala's daughter and MP from his Nepali Congress party Sujata Koirala said that it was impossible to hold polls under the present situation when there was no law and order.
"About 95 percent of our senior party members feel that," she said. They also hold Home Minister Krishna Prasad Sitaula responsible for the situation and feel he should have resigned long ago.
"But no one is willing to say that aloud."