Three suicide bombers have detonated their devices at a crowded fish market in northern Nigeria, killing at least 20 people.

Borno state police spokesman Joseph Kwaji said on Saturday that the attack happened on Friday night. Hospital officials said two patients later died from their injuries.

The bombers, all believed to be female, also wounded dozens at the fish market in Konduga, just outside the state capital of Maiduguri. The city is the birthplace of the Boko Haram insurgency and has been a frequent target.

Musa Bulama, 32, said he was lucky to have survived the blasts. “I came to the night market to buy fish for dinner when I heard a loud bang some metres behind me … I saw myself on the ground, and before I could pick up myself another one went off then, the third one again. I couldn’t stand any longer and just laid down but everywhere was in total confusion. From the wailing, one can tell that there were many casualties.”

Boko Haram continues to carry out deadly suicide bombings in Borno state and other parts of northern Nigeria as part of its campaign to establish an Islamic state. The group has increasingly used women and young people as bombers, often after abducting and indoctrinating them.