The accident happened around 11:15 a.m. at the intersection of South Broad and Market Streets.
Investigators say a Stout's Bus was traveling north on South Broad and making a left turn onto Market Street when Monserrate was hit, dragged under the bus and pinned underneath.
He was pronounced dead at the scene.
It took emergency crews nearly two hours to remove the body from underneath the bus.
The bus driver, identified as 55-year-old John Matzer of Riverside, New Jersey, was taken to Capital Health System at Fuld for routine blood tests.
Police say no criminal charges are expected to be filed, but say it is likely that he will be charged with motor vehicle offenses.
Stout Bus Company in Ewing Township owns the bus and it is under contract with Mercer County to transport employees and jurors to and from the Sovereign Bank Arena and back to the Mercer County Court House.
There were no passengers onboard the bus at the time of the crash.
The bus was impounded and will undergo a Mechanical Safety Inspection by New Jersey State Police Commercial Carrier Inspections Unit.
Anyone that witnessed the accident or has any information is encouraged to contact police at 609-989-4166 or the Trenton Police Department's confidential tip line at (609) 989-3663.
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