A gunfight broke out Thursday when separatist guerrillas who sneaked into India from Pakistan were accosted by security forces at the border in Jammu and Kashmir, police said.Police sources told IANS that a group of three to four militants infiltrated into the Indian side of the international border at Arnia in R.S. Pura area of Jammu district. Sources added the militants entered an abandoned army bunker."The infiltration attempt was supported by Pakistan Rangers who fired mortar shells at BSF (Border Security Force) positions in Arnia today (Thursday) morning so that the militants could sneak in," a senior police officer said here.The officer said a gun battle is on between the troopers and the militants.