A powerful explosion tore through a bus carrying elite security guards for Tunisia's president in the heart of the capital, authorities said Tuesday, killing at least 11 people in what appeared to be the latest militant attack in the North African country.

The blast hit the bus at rush hour on a main thoroughfare in Tunis, officials said, according to local media. The carnage was likely caused by a bomber who detonated explosives while on board the bus, the Reuters news agency reported, quoting a presidential source.

It was unclear whether those killed were security officers for Tunisia's presidential guard, or if the casualties included civilian bystanders. There was no immediate claim of responsibility. - Washington Post