A culture ministry official told The Associated Press there was no initial indication of damage to the monuments on the ancient citadel, which include the 5th Century B.C. Parthenon temple.
The ministry official, who spoke Wednesday on customary condition of anonymity, and the fire brigade said none of the four people — two site guards and two visitors — were seriously injured.
The hilltop UNESCO World Heritage site is Greece’s most popular archaeological site, with 3.15 million visitors last year.
Much of Greece has been beset by unusually persistent rainfall over recent days, with a hailstorm carpeting central Athens in white on Monday.
Lightning strikes Acropolis in Greece, 4 lightly injured