Cliff had said rockets, but this thing was not like any rocket Johnny had ever seen.

Some new aerial signal bomb, he guessed it, and thought how thoroughly up-to-date Cliff was in all his tools of trade.
He poised the thing on the edge of the cockpit, waited until they were rather close, and then gave it a toss overboard.

For a few seconds nothing happened.

Than, halfway to the ground a great blob of red light burst dazzlingly, lighting the adobe building with a crimson glow that floated gently earthward, suspended from its little parachute.
Cliff handed back another, and Johnny heaved it away from the plane.
It flared white; the third one, dropped almost before the door of the main building, revealed three men standing there gazing upward, their faces weird in its bluish glare.

Red, white and blue--a signal used sacrilegiously here, he thought.
Johnny circled widely and came back to find the landing place lighted by torches of some kind.