Blast heard in Afghan capital

A car bomb exploded in the Aghan capital hours after President Barack Obama left Kabul.

A bomb blast in Afghanistan

KABUL - A car bomb exploded in the Afghan capital on Wednesday, a police official said, hours after U.S. President Barack Obama left Kabul following an unannounced visit during which he signed a strategic partnership agreement.

Police chief Ayub Salangi told Reuters a car bomb exploded on Jalalabad road, the main road out of the capital heading east, where several U.S. military bases and compounds housing Westerners are located.

Salangi said one of those compounds, known as "Green Village", was the target.

Another police official said the explosion was followed by an exchange of gunfire. Afghan media said heavy casualties were feared.

A spokesman from NATO headquarters in the country said it was aware of several explosions. Reuters witnesses in the centre of the city also heard the blast.

Obama left earlier after making a televised address to Americans from Bagram Air Base north of the capital.

A U.S. embassy warning system urged staff to stay away from windows and take cover. The embassy is in the main diplomatic area in the centre of the city.