Initially, the revolutionaries falsely alleged that SAVAK intelligence agents were in pursuit of individuals who ran into the theatre and used it as an opportunity to hide in a large crowd. Later, the fugitives (or the SAVAK agents chasing them) locked the cinema doors.
The initial claim by the revolutionaries was false; they accused SAVAK agents of being after those who ran into the theater and used it as a hiding place.  Later, the fleeing individuals or the pursuing SAVAK agents locked the cinema doors.