MADRID—Authorities on the Spanish island of La Palma ordered residents of three coastal towns to stay indoors on Monday after a new stream of lava crashed into the ocean, sending thick clouds of potentially toxic gases high into the sky. A third tongue of lava from the Cumbre Vieja volcano, which has been erupting for two months, reached the water around midday (12:00 GMT) a few kilometres north of where two previous flows hit the sea. Drone footage from the local council showed white clouds billowing out of the water as the red hot molten rock slid down a cliff into the Atlantic. Residents in Tazacorte, San Borondon and parts of El Cardon were told to stay inside with doors and windows shut as strong winds blew the cloud back inland. Soldiers from the Military Emergency Unit were deployed to measure air quality in the area. The airport was also …