SAN DIEGO -- The National Transportation Safety Board launched an investigation Monday to determine why a U.S. Coast Guard vessel crashed into a recreational boat during the annual San Diego Bay Parade of Lights, killing an 8-year-old boy and injuring five other people.

Anthony DeWeese of Rancho Penasquitos was fatally injured when the 33-foot government craft hit the pleasure boat he was on about 6 p.m. Sunday. Medics took him to UCSD Medical Center, where he was pronounced dead.

The other patients were transported to the same Hillcrest trauma center and to Rady Children's Hospital in Serra Mesa for treatment of "major traumas," said Maurice Luque, a spokesman for the San Diego Fire-Rescue Department.

The Coast Guard was responding to a report of a grounded boat when the crash occurred, authorities said. None of the five people aboard the vessel was injured.

The crew involved in the accident has been suspended from sea duty and will serve in administrative capacities pending completion of investigations, USCG Capt. Thomas Farris told reporters during a late-afternoon briefing.

The 38th annual Parade of Lights featured a procession of nearly 80 yachts bedecked with holiday lights and other decorations.