The discovery of an unexploded piece of ordnance at East Beach on Chappaquiddick Saturday prompted the temporary closure of beach access at the Dike Bridge, and an all-out response from a state police bomb squad.

The ordnance was spotted by Will Gersey, a ranger for the Trustees of Reservations, during a routine beach patrol at Cape Pogue Wildlife Refuge late Saturday morning, according to Sam Hart, Islands manager for the Trustees.

Mr. Gersey radioed the Dukes County communications center at about 11 a.m. Saturday, Mr. Hart said in a statement. A response team from the Massachusetts state police subsequently flew to the Vineyard and went to the scene, along with Edgartown police, fire and paramedics, Mr. Hart said in a statement. He said Trustees rangers Michael Gately and Shannon Hurley were also at the scene.

The device turned out to be military-issued and contained white phosphorous that was “only partially consumed and extremely dangerous to disturb,” Mr. Hart wrote.

The device was destroyed by 4 p.m., the statement also said.

Responding to a text message from the Gazette Saturday, Edgartown fire chief Alex Schaeffer said the situation was resolved without incident.

The Vineyard was used for military training exercises during World War II, and it is not uncommon to find ordnance on Island beaches. In recent years the Army Corps of Engineers has spent millions of dollars removing unexploded ordnance from Chappaquiddick and West Tisbury beach fronts.

A notice posted on the Trustees Instagram page reminded members of the public who find ordnance on the beach to leave it undisturbed and notify authorities.