KABUL, May 31 (Xinhua) -- At least 40 people were killed and over 300 injured Wednesday after a powerful car bombing rocked a diplomatic district in central part of Afghanistan's capital of Kabul, an official said.

"The initial information found that 40 people were killed and more than 300 injured had been admitted to hospitals after Wednesday's blast," a public health official told Xinhua anonymously.

"The blast occurred roughly at 08:25 a.m. (local time) at 17th street of Wazir Akbar Khan locality, causing panic among the residents," witness Ahmad Fahim told Xinhua.

More than 50 vehicles were destroyed and dozens of the buildings around the site were damaged by the blast.

Dozens of the wounded were in critical conditions.

The explosive were planted in a water tanker vehicle. No group has claimed responsibility for the attack so far.