British police said Tuesday they were hunting for three sisters and their nine children who family members fear traveled to Syria to join a relative fighting there.
Khadija Dawood, Sugra Dawood and Zohra Dawood and their children — between the ages of 3 and 15 — were reported missing on June 11.
A lawyer acting for the family told NBC News' British partner ITV News that the missing sisters are believed to have a relative fighting for an extremist group in Syria.
"The suspicion, and main concern, is that the women have taken their children to Syria," Balaal Khan said.
He told ITV that the missing children's fathers were "obviously distraught" and desperate to get their kids back.
West Yorkshire Police said authorities are "extremely concerned" for the safety of the family from Bradford and working "extensively" with overseas officials to investigate the disappearance.
"Our priority is for their safe return; their families are gravely worried about them and want them home,” the force said in a statement. “One of our primary concerns is the safety and welfare of the young children.”
Police said the North East Counter Terrorism Unit was leading the investigation, adding that while officers were "keeping an open mind" but that "the possibility of the family attempting to travel to Syria is being explored."