Officials said the shooting happened at about 9:30 a.m. on Wood Street, not far from a playground.
A 12-year-old was shot in the abdomen and rushed to an area hospital.
A 36-year-old man was shot in the rib cage and was listed in critical condition, and a 31-year old man was shot in the arm and knee.
Wednesday's shooting is the latest in a string of violence in Trenton.
There have been 13 homicides in the city since the start of the stay-at-home-order was issued, officials said.