Someone is dropping rat poison on the streets of brownstone Brooklyn and has already killed at least one dog and made a human sick.

“It’s become very scary here for the residents and the kids who go to school,” said Cobble Hill resident Jennifer Lastra, 51, who has spotted the telltale aqua green pellets on four occasions in the last two weeks and still bears scars from her recent poisoning.

In Boerum Hill, Domingo Reyes’ beloved pooch Angel died after apparently eating poison off the sidewalk while Reyes walked the fluffy, white pooch on Butler Street on Oct. 17.

“Angel was his normal, greedy, little self. He was eating, playing around, bothering everybody,” recalled Reyes. That night, the dog refused to eat. “We knew something was wrong,” said Reyes.

On Sunday morning, Angel began to vomit, his mouth filled with foam and his tongue swelled. His owner considered taking him to the nearby emergency vet, but Angel improved that afternoon.

The next morning, Reyes found Angel dead.

“The vet said it was very strange that the dog would die within 24 hours,” said Reyes.

After Angel’s death, Reyes remembered two other dogs from Butler Street who had died suddenly in a similar way in recent years, amid rumors they had eaten poison.

A worker at nearby Hope Veterinary Clinic said they were aware of reports of pet poisonings.

“It must be a very black-hearted person to do such a thing. Attacking poor little defenseless animals, it’s like attacking a child,” said Reyes.

After hearing of Angel’s suspicious death, Lastra was walking her dog Salty on Nov. 30 when she spotted mysterious green powder all over the sidewalk.

Her husband took a sample to Veterinary Emergency & Referral Group, which ID’d it as rat poison.

That night, Lastra’s mouth started burning.

“My tongue had exploded,” said Lastra. Her mouth, tongue and inside cheeks bled and were full of sores. She called poison control and they said she must have gotten traces of the rat poison in her mouth and needed to take Vitamin K immediately.

Over a week after the event, her tongue is still scarred.

“I never dreamed I could get contaminated so easily.” said Lastra. “I’m a grown-up. If that was a little kid, it could have killed them.”

Salty was also affected that night: he started licking his paws incessantly and threw up twice.

More suspected poison was found in the following days.

On Dec. 2, green crushed pellets were found in two spots on Butler, between Smith and Hoyt streets. Two days later, a 6-inch-wide circle of suspected poison was discovered near the sidewalk of a school on Butler.

The Department of Environmental Protection and the NYPD both responded, and samples were taken.

“Our lab analysis has been unable to confirm if it is or is not rat poison,” a DEP spokesperson said.