Aziz Abadi, police Colonel, said that one of the prisoners was later recaptured.
Kourosh Saki, a medical official, said the wounded people, including three guards, received medical care but were later allowed to leave hospital.
"There were no deaths in the aftermath of the explosion," he told Fars.
Fars did not give any details on who might have been responsible for the blast nor what the motive might have been.
Ilam, which is also the name of the province, is a mountainous region bordering Iraq, and home to tribal people as well as ethnic Kurds.
Bomb attacks are relatively rare in the Islamic Republic, which also borders Afghanistan and Pakistan.