At least 21 people were killed and a dozen more seriously injured in a bus accident on Sunday in Nwoya district, northwestern Uganda, according to local police.

The accident occurred around 1:00 pm local time at Wii-anaka village, Purongo sub-county, when the bus bound for Kampala collided with an oil tanker, leaving 17 dead on spot, district police commander Moses Okello told Xinhua on the phone.

Four passengers died later in the hospital while 12 were admitted to the Nwoya hospital in serious conditions, he said.

Preliminary investigation indicated that the accident occurred due to poor visibility on the road as a result of bush fire in the area.

According to police statistics, a total of 2, 677 people died in road accidents in 2009 in the East African country.