The sirens went off Tuesday morning at the Peach Bottom Atomic Power Station on the Susquehanna River.
A coroner is investigating after a man who had been competing in a Harrisburg triathlon died after suffering medical problem while in the water.
At the PEMA operations center in suburban Harrisburg, Governor Tom Corbett said the focus right now is on the central part of the state, along the Susquehanna River.
In Harrisburg, crews put sandbags around the governor’s mansion as the Susquehanna, wide even on a normal day, spilled over its banks.
The group says natural gas extraction poses two potential threats: the soup of toxic chemicals and the huge amount of water pumped down wells so natural gas comes up.