Indonesia has executed some of the 14 people on death row for drugs crimes, Indonesian media say.
The government has not confirmed which of the prisoners have been put to death - however, an official quoted by the AFP news agency said they were three Nigerians and an Indonesian.
They were executed by firing squad shortly after midnight local time.
Indonesia has faced intense criticism internationally for resuming executions.
Fourteen, mostly foreign, drug convicts were executed last year to widespread condemnation.
This, the third round of executions under President Joko Widodo, took place at Nusakambangan prison island.
"[The execution] was at 00:45," an unnamed source was quoted by Indonesia's Antara news agency as reported by the BBC.