KABUL (Reuters) - An explosion struck a bus carrying government employees during rush hour traffic in the Afghan capital of Kabul on Wednesday, wounding four people, police and witnesses said.

The blast occurred just before 5 p.m. (8.30 a.m. ET) on a major road near a university and an old parliament building.

The target appeared to be a bus carrying employees of the Ministry of Mining and Petroleum, said Sediq Seqqi, a spokesman for the Interior Ministry.

Among the wounded were three men and one woman, officials said.

Photographs from the scene showed a small bus with its windows shattered by the blast.

(Writing by Josh Smith; Editing by Robert Birsel)