A gunman killed four people after opening fire at a church in Baton Rouge, Louisiana, during a Sunday morning service.
The suspect, Anthony Bell, 25, of Baton Rouge, then fled with his wife and three children, including an infant, police said.
His wife was later found shot dead but the children were unharmed.
Mr Bell was captured hours later at an apartment complex near the Ministry of Jesus Christ Church in the northern part of the city.
"This is going to be one of the worst days in the history of our city," police chief Jeff Leduff said. "This is senseless. This is a total waste of human life."
Sgt Charles Armstrong told Associated Press that Mr Bell is accused of shooting five people at the church before fleeing. While four have been confirmed dead, the condition of the fifth person was not known.
The body of Mr Bell's wife was found at the apartment complex but it is not known where she was killed. Her name was not released.
Neither of the pair lived at the apartment.
While at first police said the three children belonged to the couple, it remained unclear whether Mr Bell was the father of all three.
The couple's two other children were found safe at a Baton Rouge residence.
Local detectives have not been able to shed any light on a motive behind the shootings.
Mr Bell was believed to have entered the church service shortly before it was due to end at 10am and began shooting.
Hours later police responded to a call about a shooting at an apartment complex, where they found the woman dead, and Mr Bell was there holding the baby, police said.