CAIRO — Egypt descended into political turmoil on Wednesday over the constitution drafted by Islamist allies of President Mohammed Morsi, and at least 211 people were wounded as supporters and opponents battled each other with firebombs, rocks, and sticks outside the presidential palace.

Four more presidential aides resigned in protest over Morsi’s handling of the crisis, and a key opponent of the Islamist president likened Morsi’s rule to that of the ousted authoritarian leader Hosni Mubarak.