Vietnamese authorities launched a manhunt for four men who broke out of a detention center last Friday by forcing their way through a ventilation system.

Pham Von Son, 43, Phan Tuong Vinh, 28, A Men, 19, and A The, 25, broke out of a house they were being held at in Dak To district in Kon Tum Province, Viet Nam News reported. Dak To police said the men escaped by cutting through the iron bars of a ventilation system with hacksaws.

The four were being detained while the authorities investigated them over allegations of theft and sex crimes. Pham had been serving a jail term at Thu Duc prison and was in custody at the house on an additional theft charge.

Three hacksaws were found in the rooms where the defendants were held. A manhunt has been launched.