A 3-year-old Brooklyn boy is in critical condition and his mother’s boyfriend has been charged with four counts of assault in connection with his injuries, police said.

Salvatore Lucchesse, 24, was also charged with acting in a manner injurious to a child.

Authorities responded to a 911 call that said the child was in cardiac arrest at his home in Gravesend on Monday. When officers arrived, they found the child soiled and unconscious. Lucchesse told police the child slipped and hit his head in the shower, and that he had given the boy CPR.

Officials said the child's injuries include a fractured skull and lacerated spleen and liver, and are not consistent with those that can occur after CPR is administered. Investigators are still trying to determine how the 3-year-old's spleen and liver were injured. The child remains in critical condition and on a ventilator at Coney Island Hospital.