A movie theater chain that has many Houston locations has changed its policy after a gunman killed a dozen people and wounded many more in a Colorado movie theater early Friday.

AMC Theatres said it will not permit guests to wear face-concealing masks in its buildings. It also will not allow fake weapons.

The chain will also not allow "any guests into our theatres in costumes that make other guests feel uncomfortable," it said in a statement.

The chain said it is reinforcing its security procedures but declined to release exactly what changes are being made.

"Local law enforcement agencies, our landlords and their and our local security teams are stepping up nationwide to ensure we provide the safest environment possible for our guests," the theater’s statement read.