Fargo, ND – Authorities are still working to determine the cause of an explosion that leveled half of a Fargo duplex and injured 13 people.

But resident Mohamed Omar says his sister smelled gas prior to the explosion and went to the basement to check on it right before the blast.

Thirteen members of the Omar family were taken to the hospital after the explosion early Tuesday. Two of Omar’s sisters were airlifted to a Twin Cities hospital.

Some neighbors reported a lightning strike shortly before the explosion. Fire Department Captain Joe Locnikar says it’s not known if that played a role in the blast.

The Omar family has lived in the twin home units for about three years. They came to the United States from Somalia eight years ago and have lived in Fargo-Moorhead for about seven of those years.