Harrison Mayor Raymond McDonough apparently suffered a massive heart attack on Wednesday afternoon.
Officials say McDonough, who was in his mid-60s, collapsed shortly after returning from lunch. He was found by an attorney who had an appointment with him.
The lifelong Harrison resident had served on the Town Council for 17 years before becoming mayor in 1995. He was credited with spearheading the redevelopment of the 1.2-square-mile Hudson County town on the Passaic River, which has about 14,000 residents.
Town Hall was closed for the day following McDonough's death. The flag there was then lowered to half-staff.
McDonough was among a number of Democratic officials statewide who supported Republican Gov. Chris Christie for re-election last year.
Governor Christie released a statement saying, "This comes as a complete shock. Mayor McDonough was a genuine, kind-hearted soul, and someone who loved his hometown and its people deeply. He was a devoted public servant, who just wanted to help and do what was best for the tight-knit town where he lived his entire life. I will miss him very much, and Mary Pat and I will keep Ray and his family in our prayers."
U.S. Sen. Cory Booker (D-NJ) also issued the following statement on the passing of McDonough, "Today, Harrison County lost a leader and life-long public servant. I offer my sincere condolences to Mrs. McDonough and the McDonough family, as well as to the dedicated staff who worked closely with him over the years. My thoughts and prayers are with them. For nearly two decades, Mayor McDonough served the people of Hudson with integrity and dedication. He will be missed."