Almost 50 people have died and another 30 have been injured in a road accident near Uganda's border with Rwanda.
The bus was travelling from Burundi and was carrying many Rwandan and Burundian schoolchildren who were returning to study in Uganda.
A truck was carrying sacks of maize to Burundi for the UN World Food Programme when it collided with the bus head-on in Kyonyo, just 4km from the Rwanda-Uganda border town of Katuna.
The BBC's Will Ross in Kampala says the impact was so great that the bus was thrown into the air and off the road killing a woman sitting in front of her home.
The Ugandan police report that 46 people died on the spot, whilst several dozen survivors with serious injuries have been transported to a hospital in the nearby town of Kabale.
Schools are currently reopening and eyewitnesses report that amongst the dead were many Rwandan and Burundian schoolchildren who were heading to Uganda to study.
Eyewitnesses describe a horrific scene, with bodies and body parts strewn amongst the bus wreckage.
Seventy died in a bus crash in Uganda last year
Police said they had not conducted a detailed investigation yet
but suspected the accident was caused by speeding.
One eyewitness said the bus was travelling at excessive speed despite a sharp bend - and was on the wrong side of the road.
The drivers of both vehicles were killed.
A team of doctors has been flown in from Rwanda to back up the
local medical staff at Kabale hospital, he added.
Uganda has an appalling record of road accidents. In July last year 70 people were killed when a bus collided with a truck laden with fuel.
And according to police records there were over 15,000 road accidents last year which killed more than 2,000 people.
Whilst most accidents are down to dangerous driving, including excessive speeding by bus drivers.
Police spokesman Asumane Mugenyi says it is not logistically possible to police roads throughout the country and has called for a national policy on driving schools.
There has however been little effort to improve road safety and at times dangerous drivers get away with serious offences by bribing police.