Chennai, Sep 23 : The Coimbatore police have tightened security in the entire district after some miscreants hurled petrol bombs on vehicles of BJP and Hindu Munnani leaders here on Friday. The attacks are alleged to be in retaliation to the arrest of Popular Front of India (PFI) leaders from Tamil Nadu and other parts of the country on Thursday. The police said that four companies of Tamil Nadu Special Police (TSP) and two companies of Rapid Action Force (RAF) have been deployed after the petrol bomb attacks came to light. Each company of TSP has 100 policemen, while each RAF company also comprises 100 cops. An officer of Coimbatore police told IANS that raids are being conducted to arrest the culprits involved in the petrol bomb attacks. The police have tightened security in and around all the religious places in the city, including temples, mosques and churches, to prevent any flare-up between communities. The police are also conducting intensive checking at the Coimbatore-Palakkad border check-posts, as the possibility of some miscreants escaping to Kerala after committing crime in Coimbatore cannot be ruled out. A senior police officer told IANS, "We have deployed nine companies of police to nab the culprits. The law will be strict on anyone who tries to violate it and police will crush all such attempts with an iron fist." On Thursday, the National Investigation Agency (NIA) had arrested 11 persons from Tamil Nadu following raids at the premises of Poplar Front of India (PFI). The arrested persons included top PFI leader from Tamil Nadu, A.M. Ismail, who is the national executive committee member of the outfit. Yassar Arafat, zonal secretary of the Dindigul unit of PFI and Fayaz Ahamad, Cuddalore district secretary of PFI, have also been arrested. /IANS