Two men sentenced for Somerset County park explosion that injured one, damaged property
MANVILLE BOROUGH, N.J. (Somerset County) — Two men were sentenced Friday in connection with a 2024 explosion at Cooper Street Park in Manville that injured a man and caused extensive property damage, according to the Somerset County Prosecutor’s Office.
Thomas Kaiser, 60, of South Plainfield, was sentenced to six years in state prison and ordered to pay approximately $38,000 in restitution. His son, Erich Kaiser, 29, of Marlboro, was sentenced to three years of probation, including a suspended 180-day jail term, and the same restitution amount.
Both men pleaded guilty on March 28 to charges stemming from the July 6, 2024, explosion, which occurred when the pair detonated a homemade explosive device in a public park, officials said.
Thomas Kaiser pleaded guilty to second-degree causing or risking widespread injury or damage, fourth-degree aggravated assault by recklessly causing bodily injury with a deadly weapon, and third-degree criminal mischief. Erich Kaiser pleaded guilty to fourth-degree aggravated assault and third-degree criminal mischief.
According to authorities, police and emergency personnel responded around 8:16 p.m. that evening after reports of a loud explosion and an injured man at Cooper Street Park. Investigators said Thomas Kaiser had brought the explosive device—essentially a metal tube filled with explosive powder—to the park, and Erich Kaiser placed and ignited it.
The blast sent shards of the device flying through the area, striking a 34-year-old man and damaging several nearby homes and vehicles.
A joint investigation by the Manville Borough Police Department, New Jersey State Police Bomb Squad, and the Bureau of Alcohol, Tobacco, Firearms and Explosives revealed that the device had been improperly constructed. Bomb squad investigators said the device was unable to contain the blast pressure, which caused it to fragment into multiple projectiles.
