Residents in westside neighborhoods reported explosion Saturday night, but police found nothing.

A loud boom that shocked residents in a section of Novato's west side Saturday night prompted about nine calls to the police, but nothing could be found as the source, police said Sunday.

Calls came in at 8:50 p.m. and two officers responded to neighborhoods around Simmons Lane and Novato Boulevard, not far from Pioneer Park and The Square shopping center. Lt. Dave Jeffries said police received "eight or nine calls in the first two or three minutes after that, but we were not able to locate a source."

Jeffries said sometimes the wider the spread of the phone calls the harder it is for responders to pinpoint its location. He said there would have been calls about a power outage had an electrical transformer blown.