An injured man is put into an ambulance after a deadly attack Sunday outside the Ministry of Rural Rehabilitation and Development in Kabul. (Rahmat Gul/AP)

A suicide bomber blew himself up Sunday near the American University, killing at least five people outside a government building where 17 people were killed in a similar attack last month.

The Sunday bombing occurred about 4:30 p.m., officials said, as workers with the Ministry of Rural Rehabilitation and Development were leaving for the day in a southwestern portion of the city named after the towering Darul Aman Palace.

Witnesses told local news outlets that the explosion was big, disrupting rush-hour traffic and ending a period of relative calm in the nation’s capital after the June attack and two attacks in April that killed 85 people, including nine Afghan journalists.

Officials did not know why the same ministry had been attacked twice in less than a month, but in both cases, the bomber waited for the workday to end.

The attack underscored a report released earlier Sunday by the U.N. Assistance Mission in Afghanistan that found 1,692 Afghan civilians have been killed in the first six months of the year, more than in any comparable period during the past decade.

UNAMA officials said the three-day cease-fire last month had offered some hope that the civilian deaths would subside.

“The brief ceasefire demonstrated that the fighting can be stopped and that Afghan civilians no longer need to bear the brunt of the war,” Tadamichi Yamamoto, the U.N. secretary general’s special representative for Afghanistan, said in a statement. “We urge parties to seize all opportunities to find a peaceful settlement — this is the best way that they can protect all civilians.”