A reunion of kidnapped daughters and their parents in Jangebe, Nigeria, turned violent on Wednesday when armed forces reportedly opened fire.
At least three people were reportedly shot at the official handover ceremony. It is unclear if there were any deaths.
Parents were said to have become frustrated at how long the ceremony was taking and started throwing stones at government officials.
The 279 girls were kidnapped by armed men while at school last Friday.
They were then freed on Tuesday.
They were then kept in the custody of the Zamfara state government, and given medical treatment in the state capital Gusau, before Wednesday's official handover ceremony.
UN experts have called for the traumatised pupils to receive urgent rehabilitation.
One mother at the reunion told AFP news agency that parents became angry at the length of the reunion because they wanted to get back home before dark, as the roads were unsafe.
No group has yet said it carried out the kidnappings.
Nigerian President Muhammadu Buhari declared a no-fly zone across the state on Tuesday, and banned all mining activities in response to the incident.