San Diego -- 10News has received a lot of phone calls from residents reporting hearing the sound of a large "boom," or explosion around 1:45 p.m. Wednesday.

While most of the people who have contacted the station have been located in the center of San Diego, calls have come from residents in Del Mar, North Park, Allied Gardens, and Cardiff.

Some of the callers reported that their homes shook as a result of the "boom," and some of them said they heard the sound twice.

Calls to the San Diego County Sheriff's Department, San Diego Fire-Rescue, and Miramar all turned up nothing. A Camp Pendleton staffer told 10News that normal training is being conducted but nothing out of the ordinary has been reported.