The three accused, all residents of Dangru village in Shamli district of Uttar Pradesh, had gone to Pakistan on April 21 and returned to India today, a customs official said.
During checking, four pistols and seven magazines were found in their luggage.
Three out of four pistols were of Turkish make, while the fourth one was Italian made, said the official.
All three were being interrogated to find out more details, he said.