Joshua Joseph was with his 6-year-old sister when she passed out inside the family home in Rockland, Massachusetts.
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Their grandmother was babysitting them, but she can't speak English.
Joshua called his father, who urged him to hang up and call 911.
That's just what he did, and he unlocked the front door to let first responders inside.
"I feel good, yeah. I was proud of myself. It's the first time I called 911, and I saved my sister's life," he said.
This week Joshua received the "Rockland Hero" award from the Rockland police and fire departments.
Joshua's sister is doing fine after recovering from a high fever.