The blast occurred in the remote Hub region in Lasbela district where devotees were attending a Sufi dance called "dhamaal" at Dargah Shah Noorani shrine.
Balochistan Interior Minister Mir Sarfaraz Bugti confirmed the blast in which "several" people were killed.
However, an official of the Edhi Trust Foundation told local media that nearly 30 people, including women and children, were dead and around 100 injured in the blast.
"Our local focal person has told that about 30 people were killed," said the Trust's Hakeem Lassi.
Bugti said it was a remote area and it would be quite a task to retrieve the dead and injured when already darkness engulfed the region. So far nobody has claimed responsibility for the attack.