(Note: An adult tooth knocked out should be handled differently.)
Baby teeth come out naturally as a child matures, but if a baby tooth is knocked out prematurely, it can be painful and cause other damage in the mouth.
Don't try to put the baby tooth back in position in the mouth. The tooth might not stay in position in a small child, and might be swallowed. Also, if the baby tooth is pushed back into the gum, the tooth might damage the adult tooth underneath, or cause an infection.
Visit your dentist as soon as possible, to make sure there is no other damage to teeth or gums, and there are no pieces of the baby tooth left in the jaw.
To stop the bleeding, the child can bite on a piece of medical gauze or clean cloth. Also, holding an ice pack on the face near the missing tooth can limit bruising and swelling. Wrap the ice pack in cloth, so the ice doesn't touch the skin directly.