(CNN) All executions are on hold in the state of Arkansas after a judge issued a restraining order on a key lethal injection drug Wednesday.

The state had earlier planned to execute eight inmates over 10 days starting April 17, before Arkansas' supply of the drug runs out at the end of the month.

Court decisions in recent weeks, both from the state and US Supreme Courts, had granted all eight inmates a temporary reprieve, but some were overturned.

The state Supreme Court granted inmate Stacey Johnson a stay Wednesday night, ruling 4-3 that he has a right to an evidentiary hearing after he requested DNA testing to prove his innocence. Johnson was convicted of murder in 1997, and had been scheduled to be executed Thursday.

Only one inmate, Ledell Lee, was still scheduled to be executed Thursday night when a Pulaski County Circuit Court judge granted a restraining order on the lethal injection drug, vecuronium bromide, purchased from distributor McKesson Medical-Surgical. Lee's execution is now also on hold.

Read More