At least 21 people were killed on Wednesday when a suspected bomb tore through a crowded shopping district in the Nigerian capital Abuja during rush hour, according to Reuters.

It was not immediately clear who was responsible for the blast and no one claimed responsibility. However, the Boko Haram terrorist group has increasingly targeted civilians in its bloody five-year insurgency.

The suspected bomb would be Abuja’s third in three months and comes as the Nigerian government and military face rising public anger over their inability to protect citizens from daily gun and bomb attacks across Africa’s most populous country.

The explosion rocked a crowded district near the popular Banex Plaza shopping centre in the upscale Wuse 2 neighbourhood just before 4:00 p.m. local time.

“After a preliminary investigation, we can confirm that 21 people were killed and 17 injured,” police spokesman Frank Mba was quoted as having told reporters at the scene, adding that one suspect had been arrested.

Another suspect was killed by soldiers as he tried to escape on a motorcycle, the spokesman for Nigeria’s National Information Center said.

Witnesses said the blast shattered windows, sent smoke billowing into the air and carved out a large crater.

Officials said the explosion hit while the district was at its busiest, packed with shoppers and rush-hour commuters.

Nigeria has been hit by a wave of terrorist attacks, most of which have been carried out by Boko Haram. Targets have included sports venues and schools teaching a secular curriculum.

Back in April, nearly 300 schoolgirls were abducted from a school by Boko Haram in a mass kidnapping which triggered international outcry.

According to a presidential committee investigating the abductions there were 395 students at the school at the time. 119 managed to avoid capture, while another 57 escaped in the first few of days of their abduction. 219 girls are still believed to be held by the group; a video released by the Islamists soon after showed them converting to Islam, presumably under duress.

On Wednesday, it was reported that terrorists from Boko Haram had kidnapped some 60 more women and girls in the northeast of the country.