Erie Police are investigating a strong-arm robbery in the city Thursday morning. It happened shortly after 2:30 Thursday morning along West 7th Street between Chestnut St. and Liberty St. A man told police he was walking down the street from his friends house when he says he was attacked by three black men, who ran off with his keys and his wallet. The man then walked to a pay phone on West 8th Street and called the police. Police say the man was not able to give a good description of his attackers. They are still investigating the scene.