A federal report on three dolphins that died shortly after Navy ships used sonar nearby has found the animals were likely affected by the same human event.

The report by the National Marine Fisheries Service says experts weren't able to determine what caused the death of the animals in Southern California in late October.

But a panel of five experts could not rule out naval or other human activities.

The fisheries service says it and the Navy are working to provide the panel with additional information requested by the experts. It's not clear when the agency will complete its review of the deaths.

The fisheries service posted its report online last month as part of a settlement with Hawaii and other environmental groups over a lawsuit challenging Navy sonar use.