Musk testing tiny submarine to help boys in cave

Elon Musk's Space X rocket company is testing a "kid-sized submarine" that could be sent to help boys trapped in a flooded Thai cave.

Musk posted videos on Twitter of the aluminum sub being tested at a swimming pool Sunday mid-afternoon California time. If the tests are successful, the sub would be placed on a 17-hour flight to Thailand.

Four of the boys were rescued on Sunday, and authorities are now working to replenish air tanks along the cave's treacherous exit route. They say rescuing the eight remaining boys and their soccer coach could take up to four days.

Video: Elon Musk/Twitter