Three persons were injured when two grenade explosions rocked Lakhimpur town Tuesday at around 9 pm. A third grenade lobbed at a petrol pump did not explode. Sources quoting eye-witnesses said the grenades were hurled from a red Maruti car in at least two of the three spots. Although intelligence reports had indicated the Paresh Barua faction of ULFA might indulge in violence,Lakhimpur SP P K Bhuyan said there is no immediate clue to ascertain the identity of the miscreants.