The four were involved in a looting incident in Kabilas of Chitwan two days ago, said the police. They had all been living in a rented house at Chhetrapur, in Bharatpur-2.
Police have recovered two pistols and six bullets from them. Ramchandra Thapa and his wife, who were arrested from Chhetrapur, were the ringleaders, said police.
The arrested have been detained at the District Police Office for further investigation. Police said they will make them public at a press conference on Wednesday afternoon.