NEW YORK (CBSNewYork) – Investigators are trying to figure out what caused an explosion inside a Brooklyn home Saturday morning, injuring four people.

Utility workers remained on the scene more than 12 hours later, though firefighters said neighbors should not be concerned, as they are not in any danger, CBS2’s Erin Logan reported.

Crews were called to the home at 151 Bay 49th Street in Gravesend shortly before 8:15 a.m. following reports of a fire.

Neighbors told Logan they were happy to hear everyone’s going to be OK, but they’re hoping for some answers soon.

Rafael Rosales said it was difficult for him to stand by and watch as the FDNY and utility workers surrounded the home with its windows blown out. He was sleeping in one of the bedrooms on the second floor when he heard a “boom” and saw fire.

He made it out safely, but it was a different story for his friend.

“My friend, he had fire in this area,” he said, referring to his arms.

Firefighters said his friend was taken to the hospital with serious but non-life-threatening injuries. Three others suffered minor injuries.

Neighbors in the immediate area said the force of the explosion was scary.

“It was pretty loud. It felt like an earthquake, it really did,” said Ricardo Rivera.

“The whole house was shaking. Glass was moving, chandeliers were moving, our furniture was moving,” Karina Bednarek said. “My mom thought it was a bomb. I thought maybe it could have been the transformer, because it happened a few years ago.”

The Fire Marshals are investigating what caused the explosion.