and his aunt.
he sneaked out of the house early that morning in the family land-speeder to look for his escaped robots.
while he was gone, the stormtroopers came and torched his house and barbecued his Uncle/Aunt.
Aunt & Uncle could have escaped in the landspeeder if it had been there.
can you imagine Uncle Owen's horror as he and his wife ran to get into the landspeeder and then realized that Luke had taken it out joyriding, despite being admonished not to do so at dinner the previous evening?