UPTON COUNTY - OSHA investigators are looking into a deadly oilfield explosion in Upton County.
But so far they haven't said what caused the blast.
The explosion killed three family members from Andrews.
It all happened around 9:30 a.m. Tuesday morning.
Officials say a four man pulling unit crew from Mason Well Service was working at the site off FM 2401.
They were contracted by Parsley Energy.
A fourth person was treated at the scene for injuries.