ALEXANDRIA, Egypt (AP) — Clashes have broken out in northern Egypt between Islamist supporters and opponents of the country’s highly contentious draft constitution.

The two sides hurled rocks and stones at each other on Friday in the Mediterranean port city of Alexandria, prompting police to fire tear gas to separate them.

The clashes add to the already tense political crisis in Egypt on the eve of the second leg of voting on the draft charter.

The Islamists had called for a massive rally outside the main mosque in the heart of Alexandria. It was not clear who started the fight.