Five leaders of Ironworkers Local 410, previously indicted in February by federal prosecutors, are facing additional charges of extortion for targeting nonunion workers who were building elementary schools and other public facilities in the Philadelphia suburbs.

According to a federal grand jury, business agents of the union would approach nonunion contractors working at the job sites and demand they hire union ironworkers. If their demands were not met, a crew from the ironworkers union called the "Shadow Gang" would "sneak into the construction site at night, use sledgehammers to smash the anchor bolts of the building, and damage equipment."

Each incident caused tens of thousands of dollars in damages and delays. Elementary schools under construction in Wallingford and Sharon Hill were targets along with a firehouse in Eddystone, an assisted living facility in Horsham, and numerous other sites in the Pennsylvania counties surrounding Philadelphia.

In February, the FBI arrested 10 of the ironworkers' leaders, including its president Joseph Dougherty, and charged them with racketeering.

Charged today with additional counts of extortion and additional allegations related to a RICO conspiracy were Dougherty, Christopher Prophet, Richard Ritchie, Edward Sweeney and William O'Donnell. Union member Francis Sean O'Donnell is facing a count related to the RICO charges, federal prosecutors said.

Authorities previously charged Dougherty and his "goon squad" in connection with attacks on workers at a Toys R Us under construction in King of Prussia, setting fire to a Quaker meetinghouse in Chestnut Hill, and threatening workers and damaging equipment at several other sites.