Authorities say that the three-year-old boy, who is named Harry, was reported missing from a home in Lowell at around 9.30am on Tuesday.
A neighbour told investigators that they saw the youngster playing in the yard of the property, which is 30 miles from Boston, at 9.15am.
“We urge any residents in the area to check their yards and their home surveillance cameras, and keep their eyes open,” said Barry Golner, acting superintendent of the Lowell Police Department. “Every tip will help us in this search.”
And he added: “Right now we’re still treating the incident as a missing person – a missing child. All our efforts are being focused on researching, retracing. We’re going to continue our efforts and we hope to have some success and hopefully find Harry sometime today.”
The child was dropped off at the house by his parents at 7am and was wearing a long-sleeve maroon shirt with grey pants.
Police say that surveillance footage shows the babysitter quickly began searching for Harry and got neighbours to help before calling in police.
Officers have searched on ATVs, bicycles and horseback and have used K-9s and drones. They have now brought in marine units and aerial and ground thermal imaging to help in the search.
“Search has resumed for missing three-year-old Harry in Lowell. Numerous agencies/units involved, including 11 MSP K9 teams, drone unit, 20 troopers from search and rescue unit, four Mounted patrols, and three divers plus Marine assets. Search area includes wetlands, swamps,” Massachusetts State Police tweeted on Wednesday.
Police say there is no evidence of foul play in the disappearance.