Srivastava said a police team had been tracking movements of well-organised criminal gangs believed to be involved in the supply of illegal arms in the NCR.
"Sources have been extensively deployed in Munger, Kolkata and other areas to develop intelligence about the movements of these gangs," Srivastava added.
Sources said Allouddin was recently freed from jail and the police had been tracking him. The four were arrested from near Shanti Van along with a cache of illegal firearms. During interrogation, they revealed that they had been active for over five years.
"They made frequent visits to Munger to buy illegal pistols. The weapons they supplied were used to commit some serious crimes. They had developed a network to supply the pistols," a senior police officer said.
Allouddin had earlier violated the arms violations thrice in Delhi and Uttar Pradesh. The others had criminal records. The police said they were likely to arrest more people linked to the network.