Unknown assailants attacked an open-air campaign rally on Monday organised by supporters of presidential candidate Abdel-Fattah El-Sisi in the northern Nile Delta's Damietta governorate
According to Al-Ahram's Arabic news website, three were injured and the canopies hosting the conference caught fire when the assailants threw Molotov cocktails before the event started in the town of Kafr Saad.
The fire was controlled and security forces arrived to secure the tents, reported Al-Ahram.
The rally, the first since candidates were given a green light to start campaigning last Saturday, comes hours before El-Sisi was expected to give his first-ever televised interview.
The pro-El-Sisi event was planned to take place on Monday evening.
Egypt's upcoming presidential elections will take place on 26-27 May, with only El-Sisi and Nasserist political Hamdeen Sabahi facing off.