As Basir Bina, a local police spokesman stated, quoted by Reuters, the mosque was also being used as a voting registration center for parliamentary elections due to take place in October.
According to him, the explosion took place in the afternoon, when people had gathered in the building for prayers.
No terrorist group has claimed responsibility for the attack. The police have launched an investigation into the attack.
The situation in the country remains quite tense, amid the country's security forces cracking down on militants and terror groups, such as the Taliban and Daesh.*
Parliamentary and district council elections are planned for October 2018 in Afghanistan; voter registration in the country started on April 14. Afghan President Ashraf Ghani had offered the radical Taliban group to return to the peace process as a political movement and take part in the elections. The Taliban has refused the proposal.
*Taliban, Daesh — terrorist groups, outlawed in Russia and a lot of other countries