One was killed and seven others were injured when armed people attacked early Saturday a bus carrying political security personnel in Yemen's capital Sana'a, sources reported.

Conflicting reports surfaced, with some noting the bus came under a hail of bullets, and others saying the attackers threw a bomb on the but while putting agents at checkpoints, the source said.

A security source confirmed the incident but said none was hurt, it added.

It is the first time a bus of the political security system, which usually sends covert agents to guard its vehicles, has been attacked.

The authorities have not accused any group, and none has claimed responsibility for the attack that came amid similar attacks against security officers and their cars, security patrols and checkpoints and offices in the south.