A convicted hit man was been executed for a triple murder in Houston nearly 14 years ago.

Christopher Coleman, 37, was condemned for his part in a scheme by a Colombian man who hoped to eliminate a drug debt by staging a robbery. Four people wound up shot in a car on a dead-end street. Three of them, including a 3-year-old boy, died.

Coleman was pronounced dead Tuesday at 6:22 p.m. CDT (2322 GMT), eight minutes after lethal drugs began flowing into his arms.

The lethal injection, the 18th this year in Texas, was carried out after Coleman's lawyers lost late appeals at the U.S. Supreme Court.

The Texas Board of Pardons and Paroles earlier rejected a clemency request for Coleman.