A teenage girl attempting to sail solo around the world has gone missing after sending out distress signals in the Indian Ocean, according to a CNN affiliate in her hometown.

Abby Sunderland, 16, of Thousand Oaks, California, has not been heard from since losing contact with her family during a storm Thursday, her brother told CNN affiliate KTLA in Los Angeles.

Sunderland activated her emergency beacon locating devices an hour after losing contact with her family, and a rescue effort is under way. The nearest boat is believed to be at least 40 hours away, according to KTLA.