When B-3 police officer Daniel Oliveira arrived at a home on Ellington Street around 2:30 a.m. Saturday, the scene couldn’t have been more intense. A two-year-old boy was lying unresponsive on the bed, having been found by his grandmother in the middle of the night crying, shaking, and turning purple.

Told on his arrival of the emergency in the first-floor apartment, Oliveira took over from an adult trying to perform CPR, and began compressions on the toddler’s chest, according to a police report, as the child slowly began breathing while lying on his side.

The boy was then transported to Boston Medical Center for evaluation and fact-finding.