A 29-year-old man was arrested and accused of throwing his girlfriend's 4-year-old into the frigid waters off Constitution Beach in East Boston on Monday, according to Massachusetts State Police.

Mikel Anthony Hilerio dropped his girlfriend off at her job before taking her 4-year-old twin boys to the beach and putting them in the water, troopers said.

When the troopers arrived on scene, they said they found the children “shaking uncontrollably” after having been exposed to the cold water and cold air.

According to the National Oceanic and Atmospheric Administration (NOAA), coastal waters in Boston were about 47 degrees Fahrenheit Monday.

They were taken to Massachusetts General Hospital for evaluation.

Hilerio has been charged with two counts of reckless endangerment to children and operating with a suspended or revoked license.

Hilerio refused an evaluation by a drug recognition expert, police said.

In court Tuesday, prosecutors played a cell phone video showing a man apparently tossing a child into the water off Constitution Beach.

The Department of Children and Families has been notified.