The shooting victim was identified by family members as 27-year-old Cullen Green.
Green says he fell asleep in a restroom outside the main hall at The Barn at Four Pines Ranch after being involved in a wedding Sunday evening and woke up around 1:30 a.m.
When he saw that everyone was gone, he said he panicked and attempted to break through the front door of the main building.
The manager was inside and heard Green struggling. Harris County investigators say the manager confronted him and they began to fight. That's when they say the manager pulled out a gun and shot Green several times.
Green's brother confirmed with KTRK-TV that he attended a wedding at the venue on Sunday.
Green was taken by Life Flight to the hospital in serious condition.