The liberation of 21 of the more than 270 girls abducted from a Nigerian school in April 2014 is certainly to be celebrated. Yet, those heartwarming scenes of parents and girls joyously dancing and hugging are not the end of this terrible saga — not for the children still in the clutches of Boko Haram, the extremist Islamist group that has been spreading death and destruction across northeastern Nigeria for seven years, and perhaps not even for the girls who have been set free.

The abduction focused global attention on the evils of Boko Haram, which, like the Islamic State to which some of its factions claim allegiance, has forsaken scruples about victimizing children or anyone else. According to human-rights organizations, as many as 2,000 women and children, both girls and boys, have been abducted since 2012. And according to Unicef, the conflict has displaced 2.6 million people in what already was one of the world’s most destitute regions.

The 21 newly released girls were taken to a medical center in Abuja, the Nigerian capital, where they were being looked after by doctors and trauma experts. Their initial accounts echoed those of captives who have previously escaped or been rescued: of being offered a choice between becoming “wives” of Boko Haram fighters — a disgusting euphemism — or slaves. About half of the girls taken in 2014, they said, chose the first option and went off with the fighters. The rest were forced to labor for the group.

Aid workers believe that some captured women and girls have been either brainwashed or otherwise enticed into becoming fighters or suicide bombers.

When President Muhammadu Buhari of Nigeria was elected last year, he vowed to liberate the captives, and he had been under considerable pressure to show results.

But the return of these 21, welcome as it is in itself, is also a reminder of how much help Nigeria will need to eradicate Boko Haram, heal its victims and alleviate the suffering it has spread.