An undated photo from the Virginia Department of Corrections shows convicted sniper John Allen Muhammad, who was executed Tuesday night. (Associated Press)

The mastermind of the 2002 sniper attacks that killed 10 in the Washington, D.C., region has been executed.

John Allen Muhammad died by injection at 9:11 p.m. Tuesday at Greensville Correctional Center in Virginia, confirmed prison spokesman Larry Traylor.

Muhammad had no final words, Traylor said, adding he didn't hear Muhammad utter a word the entire time.

Muhammad was executed for killing Dean Harold Meyers at a gas station during a three-week killing spree in September and October 2002 in Maryland, Virginia and the District of Columbia. His teenage accomplice, Lee Boyd Malvo, was sentenced to life in prison.

Earlier Tuesday, Virginia Gov. Tim Kaine rejected clemency for Muhammad.

"I find no compelling reason to set aside the sentence that was recommended by the jury and then imposed and affirmed by the courts," Kaine said in a statement. "Accordingly, I decline to intervene."

Lawyers for Muhammad had asked Kaine to commute his sentence to life in prison, saying he is mentally ill.

The U.S. Supreme Court denied Muhammad's final appeal on Monday.

Some of the families of Muhammad's victims were at the prison to watch the execution.

"He basically watched my dad breathe his last breath," Cheryl Wits said. "Why shouldn't I watch his last breath?"

Malvo confessed to shooting Wits's father, Jerry Taylor, on a Tucson, Ariz., golf course in March 2002 at Muhammad's direction.

Muhammad and Malvo terrorized Washington and surrounding states as they shot people in broad daylight. The pair used a car that had been outfitted so the gunman could hide in the trunk and shoot through a hole in the body of the vehicle.

The pair were arrested by police at a Maryland rest stop.