LOS ANGELES (CBS) — A man was shot and killed Monday in the Westlake area of Los Angeles, authorities said.

The man, who was in his 40s, died at the scene, which occurred about 5:40 a.m. in the 800 block of South Green Avenue, the coroner said. Authorities withheld his name, pending family notification.

According to a preliminary investigation, the man was shot in the upper body after answering a knock at his door, said Los Angeles police officials. No arrests were reported.

(©2011 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services contributed to this report.)