A blast reverberated around the Island on Wednesday night as an off-Island team of Naval explosives experts detonated five potentially dangerous World War II-era bombs on the beach near Quansoo in West Tisbury.

On Wednesday morning a couple walking the beach near the cut between Tisbury Great Pond and the Atlantic Ocean discovered a suspicious object in the water and contacted the police.

Acting West Tisbury police chief Dan Rossi then contacted West Tisbury resident, retired Navy Seal and private explosives ordnance disposal contractor Tom Rancich, who is currently under contract by the Massacusetts Department of Environmental Protection to identify potentially hazardous ordnance on Martha’s Vineyard beaches and contact naval disposal teams if necessary.

“What you’re supposed to do when you find something like this is recognize, retreat and report, and that’s exactly what [the couple] did,” Mr. Rancich told the Gazette. “It certainly is a dangerous situation. A lot of people on the Island think all of this stuff is safe and it’s no big deal.”

When Mr. Rancich arrived on scene around midday he could not identify the ordnance and determined that it was potentially dangerous. He then alerted naval authorities, who sent a team of two explosive ordnance disposal experts from the naval station in Newport, R.I. When the explosives team arrived early that evening they discovered four additional pieces of ordnance. The area of the beach was closed by the West Tisbury police for much of Wednesday.

Mr. Rancich said that the team worked to counter-charge the main charge of the ordnance and attempted to sympathetically detonate any volatile material still available in the ordnance.

When the team finally detonated the ordnance around 9 p.m. Islanders from as far away as Lambert’s Cove reported hearing the booming report. West Tisbury police said that they were still receiving calls all of Thursday from curious residents.

“It was loud enough to where it sounded like a large person was falling in the second floor of your house if you were on the first floor,” said acting West Tisbury police chief Dan Rossi.

Mr. Rancich says that meteorology is at least partly responsible for the explosion’s far-reaching sound effects.

“It was an overcast night, so a lot of the sound from the explosion bounced back down off of the clouds,” he said.

Mr. Rancich estimates that he has had to deal with potentially dangerous ordnance washed ashore about two times a year for the past few years.

Parts of South Beach as well as Tisbury Great Pond were used for bombing and strafing practice during World War II and unexploded ordnance has continued to wash ashore or has been exposed by eroding beach even decades afterwards.

In October the Army Corps of Engineers began a new round of geophysical surveys on land and water around South Beach, Cape Pogue and the Tisbury Great Pond searching for unexploded ordnance as part of a larger five-year, $5.2 million cleanup effort funded by the Defense Environmental Restoration Program.