Chihuahua State Attorney General's Office spokesman Carlos Gonzalez said "It's unclear if this was gang or drug related," CNN reported.
The shooting victim, described in his 20s, was shot in the back in the church's parking lot while running from the scene, Gonzalez said.
The groom, his brother, uncle and best man were kidnapped, CNN said.
In 2009, Ciudad Juarez had more than 2,600 drug-related deaths, and is alleged to be the most violent city in Mexico.
CNN reports at least 870 people have been killed in Juarez so far this year.