Early photographs showed a torched bus surrounded by onlookers.

Six people were killed and many others were injured on Tuesday after a bus carrying security forces in the center of Tunis was the target of an explosion, local media reported.

The explosion was from within the bus and reports suggest it was a suicide attack.

Presidential spokesman Moez Sinaoui described the explosion as an “attack,” which struck the capital’s Mohamed V Avenue, a ministry official told AFP.

Many ambulances were seen at the scene. The explosion was so loud it could be heard from a long distance, witnesses said.

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