The explosion came from a hand grenade believed to be thrown by unknown assailants that drove by in a taxi. The grenade tore apart a bus and broke the glass windows of several cars parked beside it, according to the Middle East News Agency (MENA).
A second explosion took place at the same time targeting a bus that belongs to Misr Petroleum Company, parked in a street of Al-Zohour district in Port Said.
No injuries were reported from the second explosion.
Egypt has been hit by a wave of militant attacks since the ouster of Islamist president Mohamed Morsi last year.
Egypt's security forces have been fighting a decade long Islamist militant insurgency in Sinai.
Following Morsi's ouster, militant attacks, especially those targeting security forces, escalated, moving to other cities including the capital.
© Copyright Al-Ahram Publishing House