At least 40 people have been killed in an attack by Lord's Resistance Army rebels near Lira in northern Uganda.
The army has been unable to halt rebel activity
The rebels raided a camp which is home to thousands of displaced civilians.
A missionary described the scene as one of unprecedented cruelty, with the rebels leaving charred bodies and smouldering huts as they fled
More than one million people have fled during the 18-year war. The Ugandan army has been saying it is near to defeating the rebels.
The LRA, led by Joseph Kony, are known for kidnapping and brutalising young children, many of whom end up fighting for them.
A civilian militia was recently deployed in the area.
The BBC's Will Ross in Kampala says that according to a local official in the camp 47 people were killed, including two government soldiers.
Eyewitnesses say more than 100 LRA rebels surrounded Abiya camp and there was an exchange of fire between the rebels and the Ugandan army troops.
The rebels then overran the camp, using machetes and clubs, civilians were attacked, and those attempting to flee were shot.
The rebels set fire to over 100 huts before fleeing the area.
"It was horrific to see these poor defenceless people alone and at the mercy of these bandits. It is criminal," said Catholic priest Sebat Ayala from Lira, a town about 30 km from Abia.
Dozens of people are being treated in Lira hospital with severe burns, gunshot wounds and cuts.
This week the Ugandan military announced it will be sending troops into southern Sudan in pursuit of LRA rebels.