MONTGOMERY, Ala. (AP) — A federal judge on Monday blocked an execution scheduled for an Alabama inmate convicted of killing a police officer two decades ago.

U.S. District Judge W. Keith Watkins issued the stay for Torrey Twane McNabb, 40, who was scheduled to die Thursday night. McNabb is one of several inmates challenging Alabama's method of performing lethal injections.

Another Alabama inmate set to die earlier this month, Jeffery Lynn Borden, received a stay, and McNabb's execution also should be delayed, the judge ruled.

The state attorney general's office will appeal, spokesman Mike Lewis said.

McNabb was convicted of killing Montgomery police Officer Anderson Gordon in 1997.

Prosecutors say McNabb shot Gordon multiple times after the officer arrived at the scene of a crash that McNabb caused while fleeing a bail bondsman.

A federal judge temporarily halted the execution of Borden, 56, while Borden, McNabb and other Alabama inmates challenge the humaneness of the state's lethal injection procedure.

The inmates have challenged the state's use of the sedative midazolam at the start of executions, saying it would not reliably render them unconscious before other drugs stopped their lungs and heart.

Alabama has executed two inmates so far this year.