The US Supreme Court refused to block the execution of four federal prison inmates who are scheduled to be put to death in July and August.

The executions would mark the first use of the death penalty on the federal level since 2003.

The justices rejected an appeal from four inmates who were convicted of killing children.

The court’s action leaves no obstacles standing in the way of the executions, the first of which is scheduled for July 13.

The inmates are separately asking a federal judge in Washington to impose a new delay on their executions over other legal issues that have yet to be resolved.

The federal prison in Indiana where the executions would take place, USP Terre Haute, has struggled to combat the coronavirus pandemic behind bars.

One inmate there has died from Covid-19.

The inmates scheduled for execution are:

– Danny Lee, who was convicted in Arkansas of killing a family of three, including an eight-year-old;

– Wesley Ira Purkey, of Kansas, who raped and murdered a 16-year-old girl and killed an 80-year-old woman;

– Dustin Lee Honken, who killed five people in Iowa, including two children;

– Keith Dwayne Nelson, who kidnapped a 10-year-old girl who was rollerblading in front of her Kansas home and raped her in a forest behind a church before strangling the young girl with a wire.

Three of the executions, for Lee, Purkey and Honken,  are scheduled days apart beginning July 13.

Nelson’s execution is scheduled for August 28.

The Justice Department said additional executions will be set at a later date.