CHICAGO (CBS) -- Police issued a community alert Sunday about a man who sexually assaulted three women in the Logan Square neighborhood over the past few weeks. In each attack, the attacker approached his victims from behind — and he was armed with a sharp object in two of the three attacks, police said.

In each of the assaults, a man approaches women from behind, either on the sidewalk or in the hallway of apartment buildings, and assaults them. In two cases he was armed with a sharp object, police say.