4 of ORION'S stars obscured on a clear night at Lake Atitlan

The 4 stars that frame Orion's belt disappeared. 
VERY clear night, Milky Way bright across the sky, Orion at zenith, looked up to see the 4 bright stars at Orion's corners gone from the sky!  The belt was clearly visible as were all other stars, not even a wisp of cloud. 
Surmised there were 4 objects, large, dark and very high, obstructing my view of just those 4 stars! 
This caused me great anxiety, finally after 15 minutes went into the house to gather my wits. 
When going out to look again about 5 minutes later, Orion had returned to normal.
Witness indicates that date of sighting is approximate.  PD