MANILA, Philippines ? Simultaneous with the official start of campaign period on Tuesday, the Philippine National Police intensified security and set up some 3,500 checkpoints nationwide.

The checkpoints launched by the PNP netted a total of 21 people on Tuesday for violating the election gun ban.

PNP spokesman Chief Superintendent Leonardo Espina said that of those arrested, four were policemen and 17 were civilians.

All in all, the PNP has arrested 761 persons for violating the election gun ban.

Majority of those arrested were civilians, but over 80 were members of the military and police.

PNP Director General Jesus Verzosa said elite units of the PNP, including the Special Action Force, are being used in their battle against private armies.

Other units on standby are the Regional Public Safety Management Battalions and Provincial Public Safety Management Companies.

Verzosa said the PNP also has other ?combat support assets,? which would aid in their election security preparations.

Verzosa said these assets include light armor support, water-borne and air assets, newly-acquired police helicopters with night flying capability and police commandos capable of rapid deployment and ?heli-borne? insertion into areas of operation and hostile targets.