On February 14, 1929, at about 10:30 a.m., four men burst into the SMC Cartage Co. garage (2122 N. Clark) that Moran used as a headquarters for his various criminal enterprises. Two of Capone's men were dressed as police officers. The quartet presumably announced a raid and ordered the seven men inside the garage to line up against a wall. Then they opened fire. Capone men fired more than 70 bullets into the victims. Six of the seven killed were members of Moran's gang; the seventh was an unlucky friend of one of the gang members who was simply in the wrong place at the worst possible time.
When police officers from Chicago’s 36th District arrived, they found one gang member, Frank Gusenberg, barely alive. In the few minutes before he died, they pressed him to reveal what had happened, but Gusenberg wouldn't talk. As a result, many of the details of the massacre are still unknown.
The building passed through a number of owners over the next two decades, with locals and tourists often disturbing the business to witness the bullet-pocked wall. In 1949, the building owner placed plaster over the bricks in hopes of discouraging the public from interrupting business in his warehouse. In the 1960s, the neighborhood was slated for an urban housing project and the warehouse and neighboring structures were demolished. Some of the bullet-ridden bricks were preserved, sold at auction to collectors. Some of these original bricks are on display at the Mob Museum in Las Vegas, while others remain in private collections around the country.