Afghan policemen keep watch near the site of a blast in Kabul, Afghanistan August 1, 2016. [Photo/Agencies]

KABUL - Casualties were feared in the early hours of Monday after a powerful blast rocked the Afghan capital of Kabul when the city was plunged in darkness, witnesses said.

The huge bang was heard around the city roughly at 01:25 local time (20:55 GMT Sunday), causing panic among local residents.

"The big bang shocked me at my bed as soon as I got up I found we had no electricity. I received several phone calls from relatives. All people are trying to find what is happening but nobody knows what is exactly going on," witness Ahmad Farshad from western Kabul told Xinhua.

"The nature of the blast looked like a truck bombing which occurred a couple of months ago in central Kabul. The electricity was reconnected to the city about 10 minutes after the blast." Farshad said.

No official was immediately available to make comments. However, unofficial sources said that the blast was triggered by a car bombing followed by gunfires on the eastern outskirts of the city.