They aren't vicious. If the rabbit kicked out and hurt/killed the pig it would be an accident. They need companions of their own species, what works best is usually neutered male/female or female/female pairs or trios. Also they need vastly different amounts of space. The minimum amount of space for 2 small or medium rabbits is 36 square feet, preferably more. A good amount of space for 2 guinea pigs is 10 square feet.
Echo everything said already. Some pet shops say it's okay and they should be avoided as this is a definite no.
Please also bear in mind that rabbits are not great pets for children as they don't really like being picked up so kids can lose interest very quickly. Both rabbits and GPs should be kept in pairs with one of their own kind and all rabbits should be neutered for their health. Rabbits also need annual vaccinations. GPs are happier to be handled and are chattier. They make much better pets for children. They are also excellent lawn mowers.