At least eight people, including three policemen, have been killed during clashes between troops and Maoists in south-western Nepal, authorities say.
The rebels abandoned their four-month truce earlier this month
Scores of people have also been injured in the fighting which broke out in the town of Nepalganj after rebels attacked a number of police check posts.
The authorities said four rebels had died and the attack had been repulsed.
The bloodshed is some of the worst since the rebels ended a four-month unilateral truce earlier this month.
The BBC's Sushil Sharma in Kathmandu says the fighting in Nepalganj occurred in a crowded residential area prompting fears of civilian casualties.
The authorities said the one body of one civilian had been recovered so far.
Hundreds of rebels reportedly took part in the hour-long clashes, and the authorities said that they may have suffered a lot of casualties.
There was no immediate comment from the rebels.
A BBC reporter in the region said the gunshots and explosions had been heard from a number of areas in the city.
The rebels have killed a number of policemen in recent attacks in the town after they called off the truce.
They accused the army of continued attacks. The authorities refused to match the ceasefire, saying the rebels were insincere.
King Gyanendra, who seized absolute power last February, has vowed to crush the rebels.
More than 12,000 people have died in the decade since the Maoists began their campaign aimed at replacing the monarchy with a communist republic.
During the four months of the rebel ceasefire the number of people killed declined significantly, Nepalese human rights monitors said.