PORTLAND — Portland police are investigating an aggravated assault that occurred outside Matthew’s bar at 133 Free St. Monday night.

A man spotted a couple arguing at 10:30 p.m. and when he went to intervene, the woman hit him in the chin with an object, police said. Once on the ground, the man kicked him.

A woman who also tried to intervene was hit, police said.

The suspects left before police arrived.