How was Sir Richard Burton injured during the 1855 Somaliland expedition?

During the 1855 expedition to Somaliland, Sir Richard Burton and his party were attacked by locals near Berbera. During this encounter, Burton sustained a serious injury when a javelin was hurled through his jaw. The attack also resulted in the death of one member of the party and left his colleague, John Hanning Speke, severely wounded, which forced the expedition to be abandoned.12