The terrorists are Abdul Rahman Saleh Mohammad Al-Emer, 23, who had previously been detained for participating in illegal rallies and calling for the release of detainees held in terrorism cases.
The other two have been identified as Ibrahim Saleh Mohammed Al-Emer, 20 and Abdulkarim Ibrahim Mohammed Al-Hasni, also 20. All those terrorists were never issued national identity cards.
The samples collected from the crime scene were found to have traces of nitroglycerine, a highly explosive material similar to one used in Jeddah blast.
The Interior Ministry said investigations are underway and more details would be announced soon.
The suicide attacks occurred on Monday in Jeddah, Qatif and near the Prophet’s Mosque in Madinah killing four policemen and injuring nine.
The bombing in Madinah took place in a parking lot between the city court and the mosque, visited by millions every year.