Kabul, Afghanistan (CNN) At least seven civilians were killed and another 16 were injured Tuesday in an explosion in western Afghanistan.

The blast took place at about 3 p.m. near the northern gate of the Great Mosque of Herat, said Jilani Farhad, a spokesman for Herat's governor.

Security officials inspect the scene of the blast outside the Great Mosque in Herat.

It was not immediately clear who carried out the attack. But Afghanistan is grappling with a wave of terrorism that has killed more than 150 in just the past week.

An enormous suicide blast ripped through Kabul's diplomatic quarter on May 31-- right in the middle of rush hour. At least 150 people were killed , President Ashraf Ghani said.

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It was one of the deadliest attacks in the country since the start of the war in Afghanistan in 2001, which was triggered by the US invasion is search of al Qaeda leader Osama Bin Laden after 9/11.

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