Plainclothesmen, blanket security

Police will fan out across theatres screening My Name is Khan, frisk viewers and keep an eye on Shiv Sena activists everywhere, following Tuesday's attacks.
Police Commissioner D Sivanandhan assured worried exhibitors and distributors "complete security". Filmmaker Karan Johar and distributors had met him in the morning.
Five Reserve Police companies were to be deployed in each region by Tuesday evening, and there would be "heavy frisking" at theatres after the release, JCP (Law and Order) Himanshu Roy said. "The fear is that activists can come with small blades."
There may also be plainclothesmen inside theatres, said Roy, adding viewer identification could be sought. An officer said the police will decide if they need to "show strength" inside. "We have asked each theatre to employ 500 guards."
To thwart women protesters, additional policewomen have been deployed in each region.
South Mumbai's theatres have high seating capacities and Addl CP R K Padmanabhan said INOX and Metro have been given "blanket security", with a separate cordon for distributors Shringar Films at Lamington Road.
The East, which saw the protests, gets the highest deployment as all big theatres are inside malls, Addl CP Ritesh Kumar said. There will be eparate levels of security at the mall and at the multiple screens, and separate levels for frisking everyone.

Source : http://in.news.yahoo.com/48/20100210/814/tnl-frisking-inside-eye-on-sena-activist.html

Could you please explain to me the emboldened parts?