Man, dog found dead in mobile veterinary van in Queens. Here's what we know.

An investigation is underway into how a man and a dog died inside a mobile veterinary van in Flushing, Queens, on Sunday.

Police said a second man and dog survived.

The latest on the investigation

The NYPD responded to the van parked on 65th Avenue near Parsons Boulevard at around 9:30 a.m. to find a 57-year-old man and a dog dead inside. Police said they found a 73-year-old man unconscious. He is now hospitalized.

Police were waiting for autopsy results, but said a component of the investigation is if a generator seen outside of the van played a part.

A customer said the man who survived is a veterinarian known for providing low-cost services, helping save many pets. Neighbors said he has a business nearby but lives on the street, where he keeps the van parked.

Shortly after arriving to the Low Cost Vet Mobile on Sunday for her cat's surgery, Linnette Mejias was leaving shocked and in tears.

"Usually they contact, or he does. He reaches out. So it makes sense because he didn't," Mejias said. "I didn't expect this, honestly. I really hope he's OK because he's such a sweetheart."

Mejias said the veterinary team is always affordable and has saved a lot of pets, including hers.

She said her hope is "that he definitely makes a speedy recovery, that he comes home and goes back to doing what he loves to do and what we love him for."

"He said he was locked in there for four hours"

A neighbor, who asked not to be identified, said she called 911 after her son saw the owner of the van, who police have not identified, stumble out of the vehicle.

"He said he was locked in there for four hours," the neighbor said. "He was disoriented, but he was going in and out and he was the one that was able to tell me that the surgeon, the vet surgeon, was in the truck dead.

The neighbor said the man who survived "is a nice guy," adding, "I just don't like the business being done out of a truck in a residential area."