An Indian Catholic priest returned to India on Thursday after being freed from 18 months of captivity by unknown kidnappers in Yemen. Fr Tom Uzhunnalil arrived in the Indian capital and met with prime minister Narendra Modi and other government officials. Speaking to reporters at the airport, Fr Uzhunnalil thanked people who helped in his rescue. Fr Uzhunnalil had been working as a chaplain at a retirement home for more than four years in the southern Yemeni city of Aden when he was kidnapped during an attack by unknown gunmen in March 2016. The attack left 16 dead, including four nuns. Indian officials earlier this month announced the priest's rescue but gave no details. The process leading to his release was also unclear, but the Vatican thanked the sultan of Oman and Fr Uzhunnalil thanked leaders in India. The priest said after his rescue that he didn't know his kidnappers' identities or affiliations and that he was not physically harmed during his detention. After his release he was flown to Rome for a "required rest and recuperation period in Vatican City," India's foreign ministry said in a statement Thursday. Fr Uzhunnalil comes from Ramapuram in the southern Indian state of Kerala.