YAPHANK, N.Y. - More than 600 emergency workers rehearsed a response to a simulated radioactive "dirty bomb" attack in what authorities called the largest such simulation in Long Island's history.

Police, firefighters, medical workers and other personnel from 60 agencies converged Friday on the Suffolk County fire academy in Yaphank. The drill, which also involved 10 hospitals, was running through Saturday afternoon.

The scenario involved a deadly dirty bomb explosion at a federal courthouse. A dirty bomb would use conventional explosives to scatter radioactive debris.

Police had to determine the cause of the blast. Other participants practiced decontamination, detecting radiation exposure and coordinating a response involving multiple agencies.

"Interoperability is key ... to make sure we can talk to one another," said Suffolk Fire Rescue and Emergency Services Commissioner Joseph Williams.

The exercise was financed by a $175,000 federal grant, arranged by Rep. Peter King, R-N.Y.