A heavy explosion has struck a district police headquarters building in the northern Iraqi city of Mosul, killing at least four officers and wounding 14 others.

According to police and hospital officials on Sunday, the death toll could rise as rescuers were still digging in the rubble of parts of the busy two-storey building.

Four policemen were confirmed among the dead and at least seven among the wounded, medical staff said.

The blast struck the Bab al-Hadba station in central Mosul just before people began their working day at 0615 am.

Brigadier Wathiq al-Hamdani, Nineveh province's deputy police chief, told Aljazeera that two civilians had also been killed and that a large number of shops had been damaged.

"These criminals target police patrols as they attempt to maintain security in the city," al-Hamdani said. "But they will never stop us from continuing our work," he added. 

But the deputy police chief could not give details about how the attack was carried out. Some locals spoke of a car bomb attack, others of a rocket striking the building or a bomb planted inside it.

Baghdad toll

In another incident on Sunday, Colonel Riyad Abd al-Karim was assassinated on his way to work, police in the capital said.

The colonel was deputy Head of a main police department in Baghdad.

Two more Iraqis were also killed and three others injured when two mortar shells landed on their houses in al-Baladiyat neighbourhood in central Baghdad.

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