By Mary Wisniewski

CHICAGO (Reuters) - Chicago police are investigating the killing of a 9-year-old boy, and a local Catholic church is offering $5,000 for information leading to his killer's arrest, police and church officials said on Thursday.

Police found the boy, identified by local media and a church pastor as Antonio Smith, shot multiple times in a South Side backyard on Wednesday afternoon.

Smith died soon after at a children's hospital. An autopsy is pending.

The pastor, the Reverend Michael Pfleger of St. Sabina's, said that besides offering the reward, the South Side parish plans a vigil at the shooting location Thursday evening.

"You don't execute a 9-year-old boy," said Pfleger, an activist on crime issues. He said the fact that the boy was shot more than once makes it look like it was not accidental.

Chicago has seen a rash of summer gun violence, although the city's murder rate has been relatively unchanged in recent years and is down sharply from the 1990s.

In July, an 11-year-old Chicago girl, Shamiya Adams, was killed by a stray bullet at a sleepover. Tevin Lee, 18, was charged with her murder.

Pfleger said he fears that people are becoming immune to the killings, and that the latest child murder should stir as much outrage as the fatal shooting of an unarmed black teen, Michael Brown, by a police officer in Ferguson, Missouri.

Family members told WGN-TV that Smith may have been waiting for a bus or walking in the neighborhood when someone opened fire.

(Reporting by Mary Wisniewski; Editing by Jim Loney)