Nine people died during a teen-agers' outing in a cave in northern France used by German troops in World War II to conceal V1 ''doodlebug'' rockets, rescue workers said Thursday. Dead were three teen-agers, the father of one of them and five members of the team that went to look for them. The nine were apparently killed by a high concentration of carbon monoxide gas in the tunnels, outside the village of Buchy near the northern River Seine port of Rouen. The lethal gas may have been created by a fire lit by the teen-agers. The cave was used during the war to hide some of the V1 rockets that German forces fired at Britain across the English Channel.
